Acoustical insulation foams

ABSTRACT

An acoustical insulation foam having, either with or without elastification, an Asker C hardness of less than about 65, a density of about 5 to about 150 kg/m3, a cell size of about 0.05 to about 15 mm, an open cell content of 0 to about 100 volume percent, a thickness of about 1 to about 200 mm, and a width of about 100 to about 3000 mm; comprising; 
     (A) one or more alkenyl aromatic polymers, 
     (B) one or more substantially random interpolymers and 
     (C) optionally, one or more nucleating agents and 
     (D) optionally, one or more other additives; and 
     (E) one or more blowing agents.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part of application Ser. No. 09/428,575 filedon Oct. 26, 1999 allowed, which is a division of application Ser. No.09/205,938 filed on Dec. 4, 1998 pending.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

FIELD OF THE INVENTION

This invention describes a method for making acoustical insulation foamsby expanding blends of polymers comprising (A) alkenyl aromaticpolymers, and (B) vinyl or vinylidene aromatic and/or stericallyhindered aliphatic or cycloaliphatic vinyl or vinylidene substantiallyrandom interpolymers. Suitable alkenyl aromatic polymers include alkenylaromatic homopolymers and copolymers of alkenyl aromatic compounds andcopolymerizable ethylenically unsaturated comonomers. A preferredalkenyl aromatic polymer is polystyrene.

The substantially random interpolymers comprise polymer units derivedfrom ethylene and/or one or more α-olefin monomers with specific amountsof one or more vinyl or vinylidene aromatic monomers and/or stericallyhindered aliphatic or cycloaliphatic vinyl or vinylidene monomers. Apreferred substantially random interpolymer is an ethylene/styreneinterpolymer. Incorporation of the substantially random interpolymer inthe blend with the alkenyl aromatic polymer results in an increase inthe softness and flexibility of the resulting foam and an improvement inthe acoutical insulation.

BACKGROUND OF THE INVENTION

Soft and flexible foams with small cell size are typically made bycrosslinking and expanding polyolefins. Crosslinked olefinic foams aretypically made from ethylenic polymers such as low density polyethylene,ethylene vinylacetate copolymer, homogeneous ethylene and/or α-olefinhomopolymers or interpolymers comprising ethylene and/or C₃-C₂₀α-olefins including the substantially linear ethylene/α-olefininterpolymers. These include the polyolefin plastomers, such as thosemarketed by The Dow Chemical Company under the AFFINITY™ tradename andpolyethylene elastomers, such as those marketed under the ENGAGE™tradename by Du Pont Dow Elastomers PLC.

Crosslinking is achieved by conventional means such as peroxides, silaneand/or radiation. Some of the advantages of crosslinked foam overnoncrosslinked foams are smaller cell sizes (typically less than about 1mm), smooth skin and D thermoformability. However, there are severaldisadvantages of crosslinked foams, such as: (1) the chemical blowingagents used (for example, azodicarbonamide) are expensive; (2)crosslinked foams expanded with nitrogen are made in energy intensiveequipment at high pressures (typically about 10,000 to 30,000 psi); (3)the processes used to make the foams are typically batch processes whichare expensive to operate; and (4) the foams cannot be recycled. On theother hand, non-crosslinked olefinic foams are made in continuousprocesses at relatively high production rates using less expensivephysical blowing agents (such as isobutane) and the foams can berecycled (which is environmentally desirable), but these foams aredifficult to thermoform.

It is desirable to make soft and flexible non-crosslinked foams withsmall cell sizes and good aesthetics that could be used as alternativesto crosslinked foams for acoustical insulation without the disadvantageslisted above. We have surprisingly found that non-crosslinked foams madefrom blends of alkenyl aromatic polymers and specific types and amountsof substantially random interpolymers are soft and flexible with smallcell sizes and function as effective acoustical insulators. Furthermore,the foams are thermoformable and can be recycled.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section of a floating floor construction containing alayer of acoustical insulation according to the invention.

BRIEF SUMMARY OF THE INVENTION

The present invention pertains to acoustical insulation foams having,either with or without elastification, an Asker C hardness of less thanabout 65, a density of about 5 to about 150 kg/m³, a cell size of about0.05 to about 15 mm, an open cell content of 0 to about 100 volumepercent, a thickness of about 1 to about 200 mm, and a width of about100 to about 3000 mm; comprising;

(A) one or more alkenyl aromatic polymers, and wherein at least one ofsaid alkenyl aromatic polymers has a molecular weight (M_(w)) of from100,000 to 500,000; and

(B) one or more substantially random interpolymers having an I₂ of 0.1to 50 g/10 min, an M_(w)/M_(n) of 1.5 to 20; comprising;

(1) from 8 to 45 mol percent of polymer units derived from;

(a) at least one vinyl or vinylidene aromatic monomer, or

(b) at least one hindered aliphatic or cycloaliphatic vinyl orvinylidene monomer, or

(c) a combination of at least one aromatic vinyl or vinylidene monomerand at least one hindered aliphatic or cycloaliphatic vinyl orvinylidene monomer, and

(2) from 55 to 92 mol percent of polymer units derived from at least oneof ethylene and/or a C₃₋₂₀ α-olefin; and

(3) from 0 to 20 mol percent of polymer units derived from one or moreof ethylenically unsaturated polymerizable monomers other than thosederived from (1) and (2); and

(C) optionally, one or more nucleating agents and

(D) optionally, one or more other additives; and

(E) one or more blowing agents present in a total amount of from 0.4 to5.0 gram-moles per kilogram (based on the combined weight of ComponentsA and B); and

wherein said foam (either with or without elastification) has a dynamicmodulus from about 100 to about 2000 KPa, and a damping ratio of greaterthan about 10.

Definitions

All references herein to elements or metals belonging to a certain Grouprefer to the Periodic Table of the Elements published and copyrighted byCRC Press, Inc., 1989. Also any reference to the Group or Groups shallbe to the Group or Groups as reflected in this Periodic Table of theElements using the IUPAC system for numbering groups.

Any numerical values recited herein include all values from the lowervalue to the upper value in increments of one unit provided that thereis a separation of at least 2 units between any lower value and anyhigher value. As an example, if it is stated that the amount of acomponent or a value of a process variable such as, for example,temperature, pressure, time and the like is, for example, from 1 to 90,preferably from 20 to 80, more preferably from 30 to 70, it is intendedthat values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 etc. areexpressly enumerated in this specification. For values which are lessthan one, one unit is considered to be 0.0001, 0.001, 0.01 or 0.1 asappropriate. These are only examples of what is specifically intendedand all possible combinations of numerical values between the lowestvalue and the highest value enumerated are to be considered to beexpressly stated in this application in a similar manner.

The term “hydrocarbyl” as employed herein means any aliphatic,cycloaliphatic, aromatic, aryl substituted aliphatic, aryl substitutedcycloaliphatic, aliphatic substituted aromatic, or aliphatic substitutedcycloaliphatic groups.

The term “hydrocarbyloxy” means a hydrocarbyl group having an oxygenlinkage between it and the carbon atom to which it is attached.

The term “copolymer” as employed herein means a polymer wherein at leasttwo different monomers are polymerized to form the copolymer.

The term “interpolymer” is used herein to indicate a polymer wherein atleast two different monomers are polymerized to make the interpolymer.This includes copolymers, terpolymers, etc.

The term “soft foam” is used herein to indicate a foam having an Asker Chardness of less than about 65, preferably less than about 60, morepreferably less than about 55 at a foam density of about 95 kg/m³ orless.

The term “small cell size” is used herein to indicate a foam having acell size of less than about 1.8 mm.

The term “acoustical insulation foam” is used herein to indicate a foamhaving a dynamic modulus of less than about 2000 kPa and/or a dampingratio greater than about 10.

The term elastification” as used herein refers to the process by whichthe dynamic modulus, and therefore the dynamic stiffness, of a foam canbe reduced somewhat by mechanically stressing the foam. This can beaccomplished by compressing a foam in the range of from about 10 toabout 96, preferably from about 20 to about 95, most preferably fromabout 40 to about 95 percent of the original thickness. Elastificationtends to open cells and to crease cell struts so that the foam issoftened and the dynamic stiffness correspondingly reduced.

DETAILED DESCRIPTION OF THE INVENTION

The invention especially covers foams comprising blends of one or morealkenyl aromatic homopolymers, or copolymers of alkenyl aromaticmonomers, and/or copolymers of alkenyl aromatic monomers with one ormore copolymerizeable ethylenically unsaturated comonomers (other thanethylene or linear C₃-C₁₂ α-olefins) with at least one substantiallyrandom interpolymer. The foams of this invention have softness andflexibility comparable to traditional cross linked olefinic foams ofsimilar densities.

The alkenyl aromatic polymer material may further include minorproportions of non-alkenyl aromatic polymers. The alkenyl aromaticpolymer material may be comprised solely of one or more alkenyl aromatichomopolymers, one or more alkenyl aromatic copolymers, a blend of one ormore of each of alkenyl aromatic homopolymers and copolymers, or blendsof any of the foregoing with a non-alkenyl aromatic polymer. Regardlessof composition, the alkenyl aromatic polymer material comprises greaterthan 50 and preferably greater than 70 weight percent alkenyl aromaticmonomeric units. Most preferably, the alkenyl aromatic polymer materialis comprised entirely of alkenyl aromatic monomeric units.

Suitable alkenyl aromatic polymers include homopolymers and copolymersderived from alkenyl aromatic compounds such as styrene,alphamethylstyrene, ethylstyrene, vinyl benzene, vinyl toluene,chlorostyrene, and bromostyrene. A preferred alkenyl aromatic polymer ispolystyrene. Minor amounts of monoethylenically unsaturated compoundssuch as C₂₋₆ alkyl acids and esters, ionomeric derivatives, and C₄₋₆dienes may be copolymerized with alkenyl aromatic compounds. Examples ofcopolymerizable compounds include acrylic acid, methacrylic acid,ethacrylic acid, maleic acid, itaconic acid, acrylonitrile, maleicanhydride, methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butylacrylate, methyl methacrylate, vinyl acetate and butadiene.

For purposes of this invention, a alkenyl aromatic polymer is amelt-processable polymer or melt processable impact-modified polymerhaving at least 50%, preferably at least about 70% and most preferablyat least 90% of its weight in the form of polymerized vinyl aromaticmonomers as represented by the structure:

H₂C═CRAr

wherein R is hydrogen or an alkyl radical that preferably has no morethan three carbon atoms and Ar is an aromatic group. R is preferablyhydrogen or methyl, most preferably hydrogen. Suitable aromatic groupsAr include phenyl and naphthyl groups. The aromatic group Ar may besubstituted. Halogen (such as Cl, F, Br), alkyl (especially C₁-C₄ alkylsuch as methyl, ethyl, propyl and t-butyl), C₁-C₄ haloalkyl (such aschloromethyl or chloroethyl) and alkoxyl (such as methoxyl or ethoxyl)substituents are all useful. Styrene, para-vinyl toluene, α-methylstyrene, 4-methoxy styrene, t-butyl styrene, chlorostyrene, vinylnaphthalene and the like are all useful monovinylidene aromaticmonomers. Styrene is especially preferred.

The alkenyl aromatic polymer may be a homopolymer of a vinyl aromaticmonomer as described above. Polystyrene homopolymers are the mostpreferred alkenyl aromatic polymers. Interpolymers of two or more vinylaromatic monomers are also useful.

Although not critical, the alkenyl aromatic polymer may be characterizedas having a high degree of syndiotactic configuration; i.e., thearomatic groups are located alternately at opposite directions relativeto the main chain consisting of carbon-carbon bonds. Homopolymers ofvinyl aromatic polymers that have syndiotacticity of 75% r diad orgreater or even 90% r diad or greater as measured by 13C NMR are usefulherein.

The alkenyl aromatic polymer may also contain repeating units derivedfrom one or more other monomers that are copolymerizable with the vinylaromatic monomer. Suitable such monomers include N-phenyl maleimide;acrylamide; ethylenically unsaturated nitriles such as acrylonitrile andmethacrylonitrile; ethylenically unsaturated carboxylic acids andanhydrides such as acrylic acid, methacrylic acid, fumaric anhydride andmaleic anhydride; esters of ethylenically unsaturated acids such asC₁-C₈ alkyl acrylates and methacrylates, for example n-butyl acrylateand methyl methacrylate; and conjugated dienes such as butadiene orisoprene. The interpolymers of these types may be random, block or graftinterpolymers. Blends of interpolymers of this type with homopolymers ofa vinyl aromatic monomer can be used. For example, styrene/C₄-C₈ alkylacrylate interpolymers and styrene-butadiene interpolymers are suitableas impact modifiers when blended into polystyrene. Such impact-modifiedpolystyrenes are useful herein.

In addition, suitable alkenyl aromatic polymers include those modifiedwith rubbers to improve their impact properties. The modification canbe, for example, through blending, grafting or polymerization of a vinylaromatic monomer (optionally with other monomers) in the presence of arubber compound. Examples of suitable rubbers are homopolymers of C₄-C₆conjugated dienes such as butadiene or isoprene; ethylene/propyleneinterpolymers; interpolymers of ethylene, propylene and a nonconjugateddiene such as 1,6-hexadiene or ethylidene norbornene; C₄-C₆ alkylacrylate homopolymers or interpolymers, including interpolymers thereofwith a C₁-C₄ alkyl acrylate. The rubbers are conveniently prepared byanionic solution polymerization techniques or by free radical initiatedsolution, mass or suspension polymerization processes. Rubber polymersthat are prepared by emulsion polymerization may be agglomerated toproduce larger particles having a multimodal particle size distribution.

Preferred impact modified alkenyl aromatic polymers are prepared bydissolving the rubber into the vinyl aromatic monomer and any comonomersand polymerizing the resulting solution, preferably while agitating thesolution so as to prepare a dispersed, grafted, impact modified polymerhaving rubber domains containing occlusions of the matrix polymerdispersed throughout the resulting polymerized mass. In such products,polymerized vinyl aromatic monomer forms a continuous polymeric matrix.Additional quantities of rubber polymer may be blended into the impactmodified polymer if desired.

Commercial HIPS (high impact polystyrene), ABS(acrylonitrile-butadiene-styrene) and SAN (styrene-acrylonitrile) resinsthat are melt processable are also useful as blend components of thepresent invention.

The alkenyl aromatic polymer has a molecular weight such that it can bemelt processed with a blowing agent to form a cellular foam structure.Preferably, the alkenyl aromatic polymer has a melting temperature ofabout 160° C. to about 310° C.

The term “substantially random” (in the substantially randominterpolymer comprising polymer units derived from ethylene and one ormore α-olefin monomers with one or more vinyl or vinylidene aromaticmonomers and/or aliphatic or cycloaliphatic vinyl or vinylidenemonomers) as used herein means that the distribution of the monomers ofsaid interpolymer can be described by the Bernoulli statistical model orby a first or second order Markovian statistical model, as described byJ. C. Randall in POLYMER SEQUENCE DETERMINATION, Carbon-13 NMR Method,Academic Press New York, 1977, pp. 71-78. Preferably, substantiallyrandom interpolymers do not contain more than 15 percent of the totalamount of vinyl aromatic monomer in blocks of vinyl aromatic monomer ofmore than 3 units. More preferably, the interpolymer is notcharacterized by a high degree of either isotacticity orsyndiotacticity. This means that in the carbon⁻¹³ NMR spectrum of thesubstantially random interpolymer the peak areas corresponding to themain chain methylene and methine carbons representing either meso diadsequences or racemic diad sequences should not exceed 75 percent of thetotal peak area of the main chain methylene and methine carbons.

The interpolymers used to prepare the foams of the present inventioninclude the substantially random interpolymers prepared by polymerizingi) ethylene and/or one or more α-olefin monomers and ii) one or morevinyl or vinylidene aromatic monomers and/or one or more stericallyhindered aliphatic or cycloaliphatic vinyl or vinylidene monomers, andoptionally iii) other polymerizable ethylenically unsaturatedmonomer(s). Suitable α-olefins include for example, α-olefins containingfrom 3 to about 20, preferably from 3 to about 12, more preferably from3 to about 8 carbon atoms. Particularly suitable are ethylene,propylene, butene-1, 4-methyl-1-pentene, hexene-1 or octene-1 orethylene in combination with one or more of propylene, butene-1,4-methyl-1-pentene, hexene-1 or octene-1. These α-olefins do not containan aromatic moiety.

Other optional polymerizable ethylenically unsaturated monomer(s)include norbornene and C₁₋₁₀ alkyl or C₆₋₁₀ aryl substitutednorbornenes, with an exemplary interpolymer beingethylene/styrene/norbornene.

Suitable vinyl or vinylidene aromatic monomers which can be employed toprepare the interpolymers include, for example, those represented by thefollowing formula:

wherein R¹ is selected from the group of radicals consisting of hydrogenand alkyl radicals containing from 1 to about 4 carbon atoms, preferablyhydrogen or methyl; each R² is independently selected from the group ofradicals consisting of hydrogen and alkyl radicals containing from 1 toabout 4 carbon atoms, preferably hydrogen or methyl; Ar is a phenylgroup or a phenyl group substituted with from 1 to 5 substituentsselected from the group consisting of halo, C₁₋₄-alkyl, andC₁₋₄-haloalkyl; and n has a value from zero to about 4, preferably fromzero to 2, most preferably zero. Exemplary vinyl aromatic monomersinclude styrene, vinyl toluene, α-methylstyrene, t-butyl styrene,chlorostyrene, including all isomers of these compounds, and the like.Particularly suitable such monomers include styrene and lower alkyl- orhalogen-substituted derivatives thereof. Preferred monomers includestyrene, α-methyl styrene, the lower alkyl-(C₁-C₄) or phenyl-ringsubstituted derivatives of styrene, such as for example, ortho-, meta-,and para-methylstyrene, the ring halogenated styrenes, para-vinyltoluene or mixtures thereof, and the like. A more preferred aromaticvinyl monomer is styrene.

By the term “sterically hindered aliphatic or cycloaliphatic vinyl orvinylidene compounds”, it is meant addition polymerizable vinyl orvinylidene monomers corresponding to the formula:

wherein A¹ is a sterically bulky, aliphatic or cycloaliphaticsubstituent of up to 20 carbons, R¹ is selected from the group ofradicals consisting of hydrogen and alkyl radicals containing from 1 toabout 4 carbon atoms, preferably hydrogen or methyl; each R² isindependently selected from the group of radicals consisting of hydrogenand alkyl radicals containing from 1 to about 4 carbon atoms, preferablyhydrogen or methyl; or alternatively R¹ and A¹ together form a ringsystem. Preferred aliphatic or cycloaliphatic vinyl or vinylidenecompounds are monomers in which one of the carbon atoms bearingethylenic unsaturation is tertiary or quaternary substituted. Examplesof such substituents include cyclic aliphatic groups such as cyclohexyl,cyclohexenyl, cyclooctenyl, or ring alkyl or aryl substitutedderivatives thereof, tert-butyl, norbornyl, and the like. Most preferredaliphatic or cycloaliphatic vinyl or vinylidene compounds are thevarious isomeric vinyl-ring substituted derivatives of cyclohexene andsubstituted cyclohexenes, and 5-ethylidene-2-norbornene. Especiallysuitable are 1-, 3-, and 4-vinylcyclohexene. Simple linear non-branchedα-olefins including for example, α-olefins containing from 3 to about 20carbon atoms such as propylene, butene-1, 4-methyl-1-pentene, hexene-1or octene-1 are not examples of sterically hindered aliphatic orcycloaliphatic vinyl or vinylidene compounds.

The substantially random interpolymers include the pseudo-randominterpolymers as described in EP-A-0,416,815 by James C. Stevens et al.and U.S. Pat. No. 5,703,187 by Francis J. Timmers, both of which areincorporated herein by reference in their entirety. The substantiallyrandom interpolymers can be prepared by polymerizing a mixture ofpolymerizable monomers in the presence of one or more metallocene orconstrained geometry catalysts in combination with various cocatalysts.Preferred operating conditions for such polymerization reactions arepressures from atmospheric up to 3000 atmospheres and temperatures from−30° C. to 200° C. Polymerizations and unreacted monomer removal attemperatures above the autopolymerization temperature of the respectivemonomers may result in formation of some amounts of homopolymerpolymerization products resulting from free radical polymerization.

Examples of suitable catalysts and methods for preparing thesubstantially random interpolymers are disclosed in U.S. applicationSer. No. 702,475, filed May 20, 1991 (EP-A-514,828); as well as U.S.Pat. Nos.: 5,055,438; 5,057,475; 5,096,867; 5,064,802; 5,132,380;5,189,192; 5,321,106; 5,347,024; 5,350,723; 5,374,696; 5,399,635;5,470,993; 5,703,187; and 5,721,185 all of which patents andapplications are incorporated herein by reference.

The substantially random α-olefin/vinyl aromatic interpolymers can alsobe prepared by the methods described in JP 07/278230 employing compoundsshown by the general formula

where Cp¹ and Cp² are cyclopentadienyl groups, indenyl groups, fluorenylgroups, or substituents of these, independently of each other; R¹ and R²are hydrogen atoms, halogen atoms, hydrocarbon groups with carbonnumbers of 1-12, alkoxyl groups, or aryloxyl groups, independently ofeach other; M is a group IV metal, preferably Zr or Hf, most preferablyZr; and R³ is an alkylene group or silanediyl group used to cross-linkCp¹ and Cp²).

The substantially random α-olefin/vinyl aromatic interpolymers can alsobe prepared by the methods described by John G. Bradfute et al. (W. R.Grace & Co.) in WO 95/32095; by R. B. Pannell (Exxon Chemical Patents,Inc.) in WO 94/00500; and in Plastics Technology, p. 25 (September1992), all of which are incorporated herein by reference in theirentirety.

Also suitable are the substantially random interpolymers which compriseat least one α-olefin/vinyl aromatic/vinyl aromatic/α-olefin tetraddisclosed in U.S. application Ser. No. 08/708,869 filed Sep. 4, 1996 andWO 98/09999 both by Francis J. Timmers et al. These interpolymerscontain additional signals in their carbon-13 NMR spectra withintensities greater than three times the peak to peak noise. Thesesignals appear in the chemical shift range 43.70-44.25 ppm and 38.0-38.5ppm. Specifically, major peaks are observed at 44.1, 43.9, and 38.2 ppm.A proton test NMR experiment indicates that the signals in the chemicalshift region 43.70-44.25 ppm are methine carbons and the signals in theregion 38.0-38.5 ppm are methylene carbons.

It is believed that these new signals are due to sequences involving twohead-to-tail vinyl aromatic monomer insertions preceded and followed byat least one α-olefin insertion, e.g. anethylene/styrene/styrene/ethylene tetrad wherein the styrene monomerinsertions of said tetrads occur exclusively in a 1,2 (head to tail)manner. It is understood by one skilled in the art that for such tetradsinvolving a vinyl aromatic monomer other than styrene and an α-olefinother than ethylene that the ethylene/vinyl aromatic monomer/vinylaromatic monomer/ethylene tetrad will give rise to similar carbon-13 NMRpeaks but with slightly different chemical shifts.

These interpolymers can be prepared by conducting the polymerization attemperatures of from about −30° C. to about 250° C. in the presence ofsuch catalysts as those represented by the formula

wherein: each Cp is independently, each occurrence, a substitutedcyclopentadienyl group π-bound to M; E is C or Si; M is a group IVmetal, preferably Zr or Hf, most preferably Zr; each R is independently,each occurrence, H, hydrocarbyl, silahydrocarbyl, or hydrocarbylsilyl,containing up to about 30 preferably from 1 to about 20 more preferablyfrom 1 to about 10 carbon or silicon atoms; each R′ is independently,each occurrence, H, halo, hydrocarbyl, hyrocarbyloxy, silahydrocarbyl,hydrocarbylsilyl containing up to about 30 preferably from 1 to about 20more preferably from 1 to about 10 carbon or silicon atoms or two R′groups together can be a C₁₋₁₀ hydrocarbyl substituted 1,3-butadiene; mis 1 or 2; and optionally, but preferably in the presence of anactivating cocatalyst. Particularly, suitable substitutedcyclopentadienyl groups include those illustrated by the formula:

wherein each R is independently, each occurrence, H, hydrocarbyl,silahydrocarbyl, or hydrocarbylsilyl, containing up to about 30preferably from 1 to about 20 more preferably from 1 to about 10 carbonor silicon atoms or two R groups together form a divalent derivative ofsuch group. Preferably, R independently each occurrence is (includingwhere appropriate all isomers) hydrogen, methyl, ethyl, propyl, butyl,pentyl, hexyl, benzyl, phenyl or silyl or (where appropriate) two such Rgroups are linked together forming a fused ring system such as indenyl,fluorenyl, tetrahydroindenyl, tetrahydrofluorenyl, oroctahydrofluorenyl.

Particularly preferred catalysts include, for example,racemic-(dimethylsilanediyl)-bis-(2-methyl-4-phenylindenyl) zirconiumdichloride, racemic-(dimethylsilanediyl)-bis-(2-methyl-4-phenylindenyl)zirconium 1,4-diphenyl-1,3-butadiene,racemic-(dimethylsilanediyl)-bis-(2-methyl-4-phenylindenyl) zirconiumdi-C1-4 alkyl,racemic-(dimethylsilanediyl)-bis-(2-methyl-4-phenylindenyl) zirconiumdi-C1-4 alkoxide, or any combination thereof and the like.

It is also possible to use the following titanium-based constrainedgeometry catalysts,[N-(1,1-dimethylethyl)-1,1-dimethyl-1-[(1,2,3,4,5-η)-1,5,6,7-tetrahydro-s-indacen-1-yl]silanaminato(2-)-N]titaniumdimethyl; (1-indenyl)(tert-butylamido)dimethyl-silane titanium dimethyl;((3-tert-butyl)(1,2,3,4,5-η)-1-indenyl)(tert-butylamido) dimethylsilanetitanium dimethyl; and((3-iso-propyl)(1,2,3,4,5-η)-1-indenyl)(tert-butyl amido)dimethylsilanetitanium dimethyl, or any combination thereof and the like.

Further preparative methods for the interpolymers used in the presentinvention have been described in the literature. Longo and Grassi(Makromol. Chem., Volume 191, pages 2387 to 2396 [1990]) and D'Annielloet al. (Journal of Applied Polymer Science, Volume 58, pages 1701-1706[1995]) reported the use of a catalytic system based on methylalumoxane(MAO) and cyclopentadienyltitanium trichloride (CpTiCl₃) to prepare anethylene-styrene copolymer. Xu and Lin (Polymer Preprints, Am. Chem.Soc., Div. Polym. Chem.) Volume 35, pages 686,687 [1994]) have reportedcopolymerization using a MgCl₂/TiCl₄/NdCl₃/ Al(iBu)₃ catalyst to giverandom copolymers of styrene and propylene. Lu et al (Journal of AppliedPolymer Science, Volume 53, pages 1453 to 1460 [1994]) have describedthe copolymerization of ethylene and styrene using aTiCl₄/NdCl₃/MgCl₂/Al(Et)₃ catalyst. Sernetz and Mulhaupt, (Macromol.Chem. Phys., v. 197, pp. 1071-1083, 1997) have described the influenceof polymerization conditions on the copolymerization of styrene withethylene using Me₂Si(Me₄Cp)(N-tert-butyl)TiCl₂/methylaluminoxaneZiegler-Natta catalysts. Copolymers of ethylene and styrene produced bybridged metallocene catalysts have been described by Arai, Toshiaki andSuzuki (Polymer Preprints, Am. Chem. Soc., Div. Polym. Chem.) Volume 38,pages 349, 350 [1997]) and in U.S. Pat. No. 5,652,315, issued to MitsuiToatsu Chemicals, Inc. The manufacture of α-olefin/vinyl aromaticmonomer interpolymers such as propylene/styrene and butene/styrene aredescribed in U.S. Pat. No. 5,244,996, issued to Mitsui PetrochemicalIndustries Ltd or U.S. Pat. No. 5,652,315 also issued to MitsuiPetrochemical Industries Ltd or as disclosed in DE 197 11 339 A1 toDenki Kagaku Kogyo KK. All the above methods disclosed for preparing theinterpolymer component are incorporated herein by reference. Also, thecopolymers of ethylene and styrene as disclosed in Polymer Preprints Vol39, No. 1, March 1998 by Toru Aria et al. can also be employed as blendcomponents for the foams of the present invention.

While preparing the substantially random interpolymer, an amount ofatactic vinyl aromatic homopolymer may be formed due tohomopolymerization of the vinyl aromatic monomer at elevatedtemperatures. The presence of vinyl aromatic homopolymer is, in general,not detrimental for the purposes of the present invention and can betolerated. The vinyl aromatic homopolymer may be separated from theinterpolymer, if desired, by extraction techniques such as selectiveprecipitation from solution with a non solvent for either theinterpolymer or the vinyl aromatic homopolymer. For the purpose of thepresent invention it is preferred that no more than 30 weight percent,preferably less than 20 weight percent based on the total weight of theinterpolymers of atactic vinyl aromatic homopolymer is present.

Preparation of the Foams of the Present Invention

The compositions of the present invention may be used to form extrudedthermoplastic polymer foam, expandable thermoplastic foam beads orexpanded thermoplastic foams, and molded articles formed by expansionand/or coalescing and welding of those particles.

The foams may take any known physical configuration, such as extrudedsheet, rod, plank, films and profiles. The foam structure also may beformed by molding expandable beads into any of the foregoingconfigurations or any other configuration.

The foams may, if required for fast cure purposes and to attainaccelerated blowing agent release, be modified by introducing amultiplicity of channels or perforations into the foam extending from asurface into the foam, the channels being free of direction with respectto the longitudinal extension of the foam. Excellent teachings of suchmodifications are disclosed in U.S. Pat. No. 5,424,016, WO 92/19439 andWO 97/22455, the entire contents of which are herein incorporated byreference.

Foam structures may be made by a conventional extrusion foaming process.The present foam is generally prepared by melt blending in which thealkenyl aromatic polymer material and one or more substantially randominterpolymers are heated together to form a plasticized or melt polymermaterial, incorporating therein a blowing agent to form a foamable gel,and extruding the gel through a die to form the foam product. Prior toextruding from the die, the gel is cooled to an optimum temperature. Tomake a foam, the optimum-temperature is at or above the blends glasstransition temperature or melting point. For the foams of the presentinvention the optimum foaming temperature is in a range in which thefoam does not collapse. The blowing agent may be incorporated or mixedinto the melt polymer material by any means known in the art such aswith an extruder, mixer, blender, or the like. The blowing agent ismixed with the melt polymer material at an elevated pressure sufficientto prevent substantial expansion of the melt polymer material and togenerally disperse the blowing agent homogeneously therein. Optionally,a nucleator may be blended in the polymer melt or dry blended with thepolymer material prior to plasticizing or melting. The substantiallyrandom interpolymers may be dry-blended with the polymer material priorto charging to the extruder, or charged to the extruder in the form of apolymer concentrate or a interpolymer/color pigment carrier material.The foamable gel is typically cooled to a lower temperature to optimizephysical characteristics of the foam structure. The gel may be cooled inthe extruder or other mixing device or in separate coolers. The gel isthen extruded or conveyed through a die of desired shape to a zone ofreduced or lower pressure to form the foam structure. The zone of lowerpressure is at a pressure lower than that in which the formable gel ismaintained prior to extrusion through the die. The lower pressure may besuperatmospheric or subatmospheric (vacuum), but is preferably at anatmospheric level.

The present foam structures may be formed in a coalesced strand form byextrusion of the compositions of the present invention through amulti-orifice die. The orifices are arranged so that contact betweenadjacent streams of the molten extrudate occurs during the foamingprocess and the contacting surfaces adhere to one another withsufficient adhesion to result in a unitary foam structure. The streamsof molten extrudate exiting the die take the form of strands orprofiles, which desirably foam, coalesce, and adhere to one another toform a unitary structure. Desirably, the coalesced individual strands orprofiles should remain adhered in a unitary structure to prevent stranddelamination under stresses encountered in preparing, shaping, and usingthe foam. Apparatuses and method for producing foam structures incoalesced strand form are seen in U.S. Pat. Nos. 3,573,152 and4,824,720, both of which are incorporated herein by reference.

The present foam structures may also be formed by an accumulatingextrusion process as seen in U.S. Pat. No. 4,323,528, which isincorporated by reference herein. In this process, low density foamstructures having large lateral cross-sectional areas are preparedby: 1) forming under pressure a gel of the compositions of the presentinvention and a blowing agent at a temperature at which the viscosity ofthe gel is sufficient to retain the blowing-agent when the gel isallowed to expand; 2) extruding the gel into a holding zone maintainedat a temperature and pressure which does not allow the gel to foam, theholding zone having an outlet die defining an orifice opening into azone of lower pressure at which the gel foams, and an openable gateclosing the die orifice; 3) periodically opening the gate; 4)substantially concurrently applying mechanical pressure by a movable ramon the gel to eject it from the holding zone through the die orificeinto the zone of lower pressure, at a rate greater than that at whichsubstantial foaming in the die orifice occurs and less than that atwhich substantial irregularities in cross-sectional area or shapeoccurs; and 5) permitting the ejected gel to expand unrestrained in atleast one dimension to produce the foam structure.

The present foam structures may also be formed into foam beads suitablefor molding into articles by expansion of pre-expanded beads containinga blowing agent. The beads may be molded at the time of expansion toform articles of various shapes. Processes for making expanded beads andmolded expanded beam foam articles are described in Plastic Foams, PartII, Frisch And Saunders, pp. 544-585, Marcel Dekker, Inc. (1973) andPlastic Materials, Brydson, 5^(th) Ed., pp. 426-429, Butterworths(1989).

Expandable and expanded beads can be made by a batch or by an extrusionprocess. The batch process of making expandable beads is essentially thesame as for manufacturing expandable polystyrene (EPS). The granules ofa polymer blend, made either by melt blending or in-reactor blending,are impregnated with a blowing agent in an aqueous suspension or in ananhydrous state in a pressure vessel at an elevated temperature andpressure. The granules are then either rapidly discharged into a regionof reduced pressure to expand to foam beads or cooled and discharged asunexpanded beads. The unexpanded beads are then heated to expand with aproper means, e.g., with steam or with hot air. The extrusion method isessentially the same as the conventional foam extrusion process asdescribed above up to the die orifice. The die has multiple holes. Inorder to make unfoamed beads, the foamable strands exiting the dieorifice are immediately quenched in a cold water bath to prevent foamingand then pelletized. Or, the strands are converted to foam beads bycutting at the die face and then allowed to expand.

The foam beads may then be molded by any means known in the art, such ascharging the foam beads to the mold, compressing the mold to compressthe beads, and heating the beads such as with steam to effect coalescingand welding of the beads to form the article. Optionally, the beads maybe impregnated with air or other blowing agent at an elevated pressureand temperature prior to charging to the mold. Further, the beads may beheated prior to charging. The foam beads may then be molded to blocks orshaped articles by a suitable molding method known in the art. (Some ofthe methods are taught in U.S. Pat. Nos. 3,504,068 and 3,953,558.)Excellent teachings of the above processes and molding methods are seenin C. P. Park, supra, p. 191, pp. 197-198, and pp. 227-229, which areincorporated herein by reference.

To make the foam beads, blends of alkenyl aromatic polymers with one ormore substantially random interpolymer are formed into discrete resinparticles such as granulated resin pellets and are; suspended in aliquid medium in which they are substantially insoluble such as water;impregnated with a blowing agent by introducing the blowing agent intothe liquid medium at an elevated pressure and temperature in anautoclave or other pressure vessel; and rapidly discharged into theatmosphere or a region of reduced pressure to expand to form the foambeads. This process is well taught in U.S. Pat. Nos. 4,379,859 and4,464,484, which are incorporated herein by reference.

U.S. Pat. No. 4,168,353, the entire contents of which are incorporatedherein by reference, describes a process in which foamed beads areprepared from a graft polymer of polyethylene and polystyrene. Styrenemonomer may also be used to form a graft polymer with one or moresubstantially random interpolymers and be used to prepare foam beads.The process involves

(I) impregnation of styrene monomer into suspended pellets of one ormore substantially random interpolymer(s) in a vessel at elevatedtemperature in the presence of a peroxide initiator to form a graftedpolymer of polystyrene with the substantially random polymer;

(II) impregnation of the product of step I with one or more blowingagents,

(III) cooling and discharging the product from step II to formunexpanded beads; and

(IV) expanding and molding the beads of step III to form a foam.

Another process for making expandable thermoplastic beads comprisesproviding an alkenyl aromatic monomer and optionally at least oneadditional monomer, which is different from, and polymerizable with saidalkenyl aromatic monomer; and dissolving in at least one of saidmonomers the substantially random interpolymers; polymerizing the firstand second monomers to form thermoplastic particles; incorporating ablowing agent into the thermoplastic particles during or afterpolymerization; and cooling the thermoplastic particles to formexpandable beads. The alkenyl aromatic monomer is present in an amountof at least about 50, preferably at least about 70, more preferably atleast about 90 wt % based on the combined weights of the polymerizeablemonomer(s).

Another process for making expandable thermoplastic beads comprises:heating the blends of alkenyl aromatic polymers with one or moresubstantially random interpolymers to form a melt polymer; incorporatinginto the melt polymer material at an elevated temperature a blowingagent to form a foamable gel; cooling the gel to an optimum temperaturewhich is one at which foaming will not occur, extruding through a diecontaining one or more orifices to form one or more essentiallycontinuous expandable thermoplastic strand(s); and pelletizing theexpandable thermoplastic strand(s) to form expandable thermoplasticbead(s). Alternatively expanded thermoplastic foam beads may be made if,prior to extruding from the die, the gel is cooled to an optimumtemperature which in this case is at or above the blends glasstransition temperature or melting point. For the expanded thermoplasticfoam beads of the present invention, the optimum foaming temperature isin a range sufficient to prevent foam collapse.

The present foam structures may also be used to make foamed films forbottle labels and other containers using either a blown film or a castfilm extrusion process. The films may also be made by a co-extrusionprocess to obtain foam in the core with one or two surface layers, whichmay or may not be comprised of the polymer compositions used in thepresent invention.

Blowing agents useful in making the present foams include inorganicblowing agents, organic blowing agents and chemical blowing agents.Suitable inorganic blowing agents include nitrogen, sulfur hexafluoride(SF₆), argon, water, air and helium. Organic blowing agents includecarbon dioxide, aliphatic hydrocarbons having 1-9 carbon atoms,aliphatic alcohols having 1-3 carbon atoms, and fully and partiallyhalogenated aliphatic hydrocarbons having 1-4 carbon atoms. Aliphatichydrocarbons include methane, ethane, propane, n-butane, isobutane,n-pentane, isopentane, neopentane, and the like. Aliphatic alcoholsinclude methanol, ethanol, n-propanol, and isopropanol. Fully andpartially halogenated aliphatic hydrocarbons include fluorocarbons,chlorocarbons, and chlorofluorocarbons. Examples of fluorocarbonsinclude methyl fluoride, perfluoromethane, ethyl fluoride,),1,1-difluoroethane (HFC-152a), fluoroethane (HFC-161),1,1,1-trifluoroethane (HFC-143a), 1,1,1,2-tetrafluoroethane (HFC-134a),1,1,2,2 tetrafluoroethane (HFC-134), 1,1,1,3,3-pentafluoropropane,pentafluoroethane (HFC-125), difluoromethane (HFC-32), perfluoroethane,2,2-difluoropropane, 1,1,1-trifluoropropane, perfluoropropane,dichloropropane, difluoropropane, perfluorobutane, perfluorocyclobutane.Partially halogenated chlorocarbons and chlorofluorocarbons for use inthis invention include methyl chloride, methylene chloride, ethylchloride, 1,1,1-trichloro-ethane, 1,1-dichloro-1-fluoroethane(HCFC-141b), 1-chloro-1,1-difluoroethane (HCFC-142b),chlorodifluoromethane (HCFC-22), 1,1-dichloro-2,2,2-trifluoroethane(HCFC-123) and 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124). Fullyhalogenated chlorofluorocarbons include trichloromonofluoromethane(CFC-11), dichlorodifluoromethane (CFC-12), trichloro-trifluoroethane(CFC-113), dichlorotetrafluoroethane (CFC-114),chloroheptafluoropropane, and dichlorohexafluoropropane. Chemicalblowing agents include azodicarbonamide, azodiisobutyro-nitrile,benzenesulfonhydrazide, 4,4-oxybenzene sulfonyl-semicarbazide, p-toluenesulfonyl semi-carbazide, barium azodicarboxylate,N,N′-dimethyl-N,N′-dinitroso-terephthalamide, trihydrazino triazine andmixtures of citric acid and sodium bicarbonate such as the variousproducts sold under the name Hydrocerol™ (a product and trademark ofBoehringer Ingelheim). All of these blowing agents may be used as singlecomponents or any mixture of combination thereof, or in mixtures withother co-blowing agents.

The amount of blowing agent incorporated into the polymer melt materialto make a foam-forming polymer gel is from about 0.4 to about 5.0gram-moles per kilogram of polymer, preferably from about 0.6 to about3.0 gram-moles per kilogram of polymer, and most preferably from about0.8 to 2.5 gram-moles per kilogram of polymer.

In addition, a nucleating agent may be added in order to control thesize of foam cells. Preferred nucleating agents include inorganicsubstances such as calcium carbonate, talc, clay, silica, bariumstearate, diatomaceous earth, mixtures of citric acid and sodiumbicarbonate, and the like. The amount of nucleating agent employed mayrange from 0 to about 5 parts by weight per hundred parts by weight of apolymer resin. The preferred range is from 0 to about 3 parts by weight.

Various additives may be incorporated in the present foam structure suchas inorganic fillers, pigments, antioxidants, acid scavengers,ultraviolet absorbers, flame retardants, processing aids, extrusionaids, permeability modifiers, antistatic agents, other thermoplasticpolymers and the like. Examples of permeability modifiers include butare not limited to glycerol monoesters. These monoesters may also serveto reduce static during foam manufacture. Examples of otherthermoplastic polymers include alkenyl aromatic homopolymers orcopolymers (having molecular weight of about 2,000 to about 50,000) andethylenic polymers.

The foam has a density of from about 10 to about 95 and most preferablyfrom about 10 to about 80 kilograms per cubic meter according to ASTMD-1622-88.

The foams may be microcellular (i.e, with a cell size of from less thanabout 0.05 mm, preferably from about 0.001 to about 0.05 mm) ormacrocellular (i.e., Cell size of about 0.05 mm or more). Themacrocellular foam has an average cell size of from about 0.05 to about15, preferably from about 0.1 to about 10.0, and more preferably fromabout 0.2 to about 5 millimeters according to ASTM D3576-77.

The present foam is particularly suited to be formed into a plank orsheet, desirably one having a thickness or minor dimension incross-section of 1 mm or more, preferably 2 mm or more, or morepreferably 2.5 mm or more. The foam width could be as large as about 1.5meter.

The present foams have an open cell content ranging from 0 to 100percent according to ASTM D2856-94.

The hardness of the present foams was measured using an Asker Cdurometer for cellular rubber and yarn in accordance with ASTM D2240-97(but with a spherical indentor of about 5 mm diameter). The Asker Chardness was less than about 65, preferably less than about 60, morepreferably less than about 55.

The foams of the present invention may be used in a variety ofapplications such as cushion packaging, athletic and recreationalproducts, egg cartons, meat trays, building and construction (e.g.,thermal insulation, acoustical insulation), pipe insulation, gaskets,vibration pads, luggage liners, desk pads shoe soles, gymnastic mats,insulation blankets for greenhouses, case inserts, display foams, etc.Examples of building and construction applications include external wallsheathing (home thermal insulation), roofing, foundation insulation, andresiding underlayment. Other applications include insulation forrefrigeration, buoyancy applications (e.g., body boards, floating docksand rafts) as well as various floral and craft applications. It shouldbe clear, however, that the foams of this invention will not be limitedto the above mentioned applications.

One preferred embodiment of the soft and flexible foams of the presentinvention is acoustical insulation foam. EP Patent No. 561216, disclosesa potential method for the elastification of expanded polystyrene (EPS)foams. DIN 4109 describes the acoustic requirements for buildings inGermany. DIN 18164-2 is the product standard for elastified EPS inimpact sound insulation, which is the dominant product for impact soundinsulation of floating floor systems. However, the boards of anelastified EPS product are typically thicker than 17 mm, and even theGerman standard for elastified EPS in impact sound insulationapplications (DIN 18164-2) does not specify elastified EPS boards with athickness below 15 mm. Thus it would be desirable to prepare anacoustical insulation foam of thickness less than 15 mm.

Properties of the Interpolymers and Blend Compositions Used to Preparethe Foams of the Present Invention

The soft and flexible of the present invention have an Asker C hardnessof less than about 65.

The molecular weight distribution (M_(w)/M_(n)) of the alkenyl aromatichomopolymers or copolymers used to prepare the foams of the presentinvention is from about 2 to about 7.

The molecular weight (Mw) of the alkenyl aromatic homopolymers orcopolymers used to prepare the foams of the present invention is fromabout 100,000 to about 500,000, preferably of from about 120,000 toabout 350,000, more preferably 130,000 to 325,000. In the case of animpact modified polymer, these molecular weight numbers refer tomolecular weight of the matrix polymer (i.e., the continuous phasepolymer of an alkenyl aromatic polymer).

The alkenyl aromatic polymer material used to prepare the foams of thepresent invention comprises greater than 50 and preferably greater than70 weight percent alkenyl aromatic monomeric units. Most preferably, thealkenyl aromatic polymer material is comprised entirely of alkenylaromatic monomeric units.

The melt index (I₂) of the substantially random interpolymer used toprepare the foams of the present invention is from about 0.1 to about50, preferably of from about 0.3 to about 30, more preferably of fromabout 0.5 to about 10 g/10 min.

The molecular weight distribution (M_(w)/M_(n)) of the substantiallyrandom interpolymer used to prepare the foams of the present inventionis from about 1.5 to about 20, preferably of from about 1.8 to about 10,more preferably of from about 2 to about 5.

In addition, minor amounts of alkenyl aromatic homopolymers orcopolymers having a molecular weight of about 2,000 to about 50,000,preferably from about 4,000 to about 25,000 can be added in an amountnot exceeding about 20 wt % (based on the combined weights ofsubstantially random interpolymer and the various alkenyl aromatichomopolymers or copolymers).

Properties of the Interpolymers and Blend Compositions Used to Preparethe Acoustical Insulation Foams of the Present Invention

The polymer compositions used to prepare the acoustical insulation foamsof the present invention comprise from about 15 to about 80, preferablyfrom about 20 to about 70, more preferably from about 30 to about 65 wt%, (based on the combined weights of substantially random interpolymerand the alkenyl aromatic homopolymers or copolymers) of one or moresubstantially random interpolymers.

The polymer compositions used to prepare the acoustical insulation foamsof the present invention comprise from about 20 to about 85, preferablyfrom about 30 to about 80, more preferably from about 35 to about 70 wt%, (based on the combined weights of substantially random interpolymerand the alkenyl aromatic homopolymers or copolymer) of one or morealkenyl aromatic homopolymers or copolymers.

The acoustical insulation foams of the present invention, either with orwithout elastification, have an Asker C hardness less than about 65,preferably less than about 60, most preferably less than about 55.

The acoustical insulation foams of the present invention, either with orwithout elastification, have a density in the range of about 5 to about150, preferably of about 6 to about 100, most preferably of about 10 toabout 50 kg/m³.

The acoustical insulation foams of the present invention, either with orwithout elastification, may be microcellular (i.e, with a cell size offrom less than about 0.05 mm, preferably from about 0.001 to about 0.05mm) or macrocellular (i.e., cell size of about 0.05 mm or more). Themacrocellular acoustical insulation foams of the present invention,either with or without elastification, have a cell size in the range ofabout 0.05 to about 15, preferably of about 0.1 to about 10, mostpreferably of about 0.2 to about 8, even more preferably from about 0.3to about 2 mm according to ASTM D3576-77.

The acoustical insulation foams of the present invention, either with orwithout elastification, have an open cell content in the range of 0 toabout 100, preferably of about 10 to about 95, most preferably of about20 to about 90 volume percent.

The acoustical insulation foams of the present invention, either with orwithout elastification, have a thickness in the range of about 1 toabout 200, preferably of about 1.5 to about 100, most preferably ofabout 2 to about 50 mm.

The acoustical insulation foams of the present invention, either with orwithout elastification, have a width in the range of about 100 to about3000, preferably of about 250 to about 2500, most preferably of about500 to about 2000 mm.

The acoustical insulation foams of the present invention, either with orwithout elastification, have a dynamic modulus from about 100 to about2000, preferably from about 100 to about 1000, most preferably fromabout 100 to about 600 KPa.

The acoustical insulation foams of the present invention, either with orwithout elastification, have a damping ratio greater than about 10,preferably greater than about 11, most preferably greater than about 12.

The acoustical insulation foams of the present invention areadvantageously (but not necessarily) elastified by a compression in therange of from about 10 to about 96, preferably from about 20 to about95, most preferably from about 40 to about 95 percent of the originalthickness. The dynamic modulus, and therefore the dynamic stiffness, ofa foam can be reduced somewhat by mechanically stressing the foam, suchas by compression. This process is referred to herein as“elastification”. Elastification tends to open cells and to crease cellstruts so that the foam is softened and the dynamic stiffnesscorrespondingly reduced. Compression is readily accomplished by, forexample, compressing the foam by about 10-96% of its original thicknessthrough a pair of rollers or under any kind of compression system.Multiple compressions may be done in order to achieve a desired dynamicmodulus or stiffness.

The foam is used as a layer of acoustical insulation in a floor or wallconstruction. A layer of the foam is installed in the wall or floor atwhich acoustical insulation is desired. The foam layer is advantageouslyinstalled in the wall or floor between weight-bearing structures andexposed surfaces. For vertical installations, the foam can be held inplace with adhesives or mechanical devices such as nails, screws,staples or rivets. For horizontal installations, it is often notnecessary to secure the foam to the underlying structure, although itmay be so secured if desired.

FIG. 1 illustrates a preferred installation. In FIG. 1, structuralsubfloor 1 is affixed to structural wall support 2. Interior wallsurface 9 is affixed to structural wall support 2 through gypsum 8.Acoustical foam layer 5 lies atop structural subfloor 1. Acoustical foamedge strip 5 a is positioned at the interface of screed 3 and structuralwall support 2. Optional ilm layer 4 separates screed 3 from acousticalfoam layer 5 and vertical acoustical foam edge strip 5 a. Exposed floorsurface 6 is positioned atop screed 3. Elastic sealing bead 7 fills anyremaining space between the exposed floor surface 6 and the interiorwall surface 9.

Screed 3 and the exposed floor surface 6 are “floating” in the sensethat they are not affixed to the structural subfloor 1 or the structuralwall support 2.

The floating floor system illustrated in FIG. 1 is convenientlyinstalled by first building the structural subfloor 1 and structuralwall support 2. The structural subfloor 1 can be made of any suitablebuilding material, including concrete, reinforced concrete, wood, steel,aluminum, plywood, particle board, plasterboard, fibrous-reinforcedgypsum playtes oriented strand boards and the like. Concrete andreinforced concrete subfloors are preferred. Acoustical foam layer 5 isinstalled over the subfloor 1. Advantageously, substantially the entiresurface of the subfloor is covered with acoustical foam layer 5. Holesmay be provided for services such as water, drains, electrical, cables,ducts, vents, and the like which must not get in contact with screed 3.In addition, the periphery of the floor is also lined with acousticalfoam edge strip 5 a, which extends upward along the structural wallsupport 2 to a height at least equal to that of the floating floor(i.e., The combined height of acoustical foam layer 5, film layer 4,screed 3 and exposed floor surface 6). As mentioned, acoustical foamlayer 5 and acoustical foam edge strip 5 a may be simply laid intoplace, or may be secured to subfloor 1 and/or structural wall support 2though adhesive or mechanical means.

As shown in FIG. 1, film layer 4 is then installed over the acousticalfoam layer 5 and acoustical foam edge strip 5 a. Screed 3 is of astructural material whose purpose is to provide a dimensionally stablesupport for the exposed floor surface as well as to provide mass thatassists in the overall acoustical performance of the floor. Screed 3 iscommonly a concrete-type or reinforced concrete-type that is poured inplace over the previously-installed acoustical foam. Film layer 4provides a continuous surface over which the concrete can be poured, sothat the concrete does not leak through spaces between separate piecesof foam that make up acoustical foam layer 5, or between acoustical foamlayer 5 and edge strips 5 a. This prevents concrete bridges betweenscreed 3 and subfloor 1 from being formed. Such bridges readily transmitsound, so their formation is to be avoided. Instead of using film layer4, acoustical foam layer 5 and edge strips 5 a can be taped at allseams, so that those spaces are sealed and leakage of the concrete isprevented.

Screed 3 can also be made from prefabricated gypsum plates, fiberreinforced gypsum plates or wood (such as a parquet floor). In thiscase, it is convenient to attached acoustical layer 5 to the plates orwood pieces prior to installation. In this manner, acoustical layer 5and screed 3 can be installed simultaneously. Screed 3 can also take theform of ceramic or other tiles embedded in a mortar bed.

In all cases, screed 3 is installed in such a way that it “floats” overacoustical foam layer 5 and is not affixed to structural subfloor 1 orstructural wall support 2.

Acoustical foam layer 5 and foam edge strip 5 a are each advantageouslyfrom about 1 to about 30, preferably from about 3 to about 25, morepreferably about 3 to about 20 mm thick.

The following examples are illustrative of the invention, but are not tobe construed as to limiting the scope thereof in any manner.

EXAMPLES

Test Methods

a) Melt Flow and Density Measurements

The molecular weight of the substantially random interpolymers used inthe present invention is conveniently indicated using a melt indexmeasurement according to ASTM D-1238, Condition 190° C./2.16 kg(formally known as “Condition (E)” and also known as I₂) was determined.Melt index is inversely proportional to the molecular weight of thepolymer. Thus, the higher the molecular weight, the lower the meltindex, although the relationship is not linear.

Also useful for indicating the molecular weight of the substantiallyrandom interpolymers used in the present invention is the Gottfert meltindex (G, cm³/10 min) which is obtained in a similar fashion as for meltindex (I₂) using the ASTM D1238 procedure for automated plastometers,with the melt density set to 0.7632, the melt density of polyethylene at190° C.

The relationship of melt density to styrene content for ethylene-styreneinterpolymers was measured, as a function of total styrene content, at190° C. for a range of 29.8% to 81.8% by weight styrene. Atacticpolystyrene levels in these samples was typically 10% or less. Theinfluence of the atactic polystyrene was assumed to be minimal becauseof the low levels. Also, the melt density of atactic polystyrene and themelt densities of the samples with high total styrene are very similar.The method used to determine the melt density employed a Gottfert meltindex machine with a melt density parameter set to 0.7632, and thecollection of melt strands as a function of time while the I₂ weight wasin force. The weight and time for each melt strand was recorded andnormalized to yield the mass in grams per 10 minutes. The instrument'scalculated I₂ melt index value was also recorded. The equation used tocalculate the actual melt density is

δ=δ_(0.7632) ×I ₂ /I ₂ Gottfert

where δ_(0.7632)=0.7632 and I₂ Gottfert=displayed melt index.

A linear least squares fit of calculated melt density versus totalstyrene content leads to an equation with a correlation coefficient of0.91 for the following equation:

δ=0.00299×S+0.723

where S=weight percentage of styrene in the polymer. The relationship oftotal styrene to melt density can be used to determine an actual meltindex value, using these equations if the styrene content is known.

So for a polymer that is 73% total styrene content with a measured meltflow (the “Gottfert number”), the calculation becomes:

δ=0.00299*73+0.723=0.9412

where 0.9412/0.7632=I₂/G# (measured)=1.23

b) Styrene Analyses

Interpolymer styrene content and the concentration of atacticpolystyrene hompolymer impurity in the ESI interpolymers are determinedusing proton nuclear magnetic resonance (¹H NMR). All proton NMR samplesare prepared in 1,1,2,2-tetrachloroethane-d₂ (tce-d₂). The resultingsolutions contain 1.6 weight percent polymer for ESI-1 and 2.4 forESI-2. The interpolymers are weighed directly into 5-mm sample tubes. A0.75-ml aliquot of tce-d₂ is added by syringe and the tube is cappedwith a tight-fitting cap. The samples are heated at 85° C. to soften theinterpolymer. To provide mixing, the capped samples are occasionallybrought to reflux using a heat gun.

Proton NMR spectra are accumulated with the sample probe at 80° C., andreferenced to the residual protons of tce-d₂ at 5.99 ppm. Data iscollected in triplicate on each sample. The following instrumentalconditions are used for analysis of the interpolymer samples:

Sweep width, 5000 hz

Acquisition time, 3.002 sec

Pulse width, 8 μsec

Frequency, 300 mhz

Delay, 1 sec

Transients, 16

The total analysis time per sample is about 10 minutes.

Initially, a spectrum for a sample of a 192,000 M_(w) polystyrene isacquired. Polystyrene has five different types of protons that aredistinguishable by proton NMR. In FIG. 1, these protons are labeled b,branch; α, alpha; o, ortho; m, meta; p, para, as shown in FIG. 1. Foreach repeating unit in the polymer, there are one branch proton,two-alpha protons, two ortho protons, two meta protons and one paraproton.

The NMR spectrum for polystyrene homopolymer includes a resonancecentered around a chemical shift of about 7.1 ppm, which is believed tocorrespond to the three ortho and para protons. It includes another peakcentered around a chemical shift of about 6.6 ppm. That peak correspondsto the two meta protons. Other peaks at about 1.5 and 1.9 ppm correspondto the three aliphatic protons (alpha and branch).

The relative intensities of the resonances for each of these protons aredetermined by integration. The integral corresponding to the resonanceat 7.1 ppm is designated PS_(7.1) below. That corresponding to theresonance at 6.6 ppm is designated PS_(6.6) and that corresponding tothe aliphatic protons (integrated from 0.8-2.5 ppm) is designatedPS_(al). The theoretical ratio for PS_(7.1):PS_(6.6):PS_(al) is 3:2:3,or 1.5:1:1.5. For atactic polystyrene homopolymer, all spectra collectedhave the expected 1.5:1:1.5 integration ratio. An aliphatic ratio of 2to 1 is predicted based on the protons labeled α and b respectively inFIG. 1. This ratio is also observed when the two aliphatic peaks areintegrated separately. Further, the ratio of aromatic to aliphaticprotons is measured to be 5 to 3, as predicted from theoreticalconsiderations.

Then, the ¹H NMR spectrum for the ESI interpolymer is acquired. Thisspectrum shows resonances centered at about 7.1 ppm, 6.6 ppm and in thealiphatic region. However, the 6.6 ppm peak is relatively much weakerfor the ESI interpolymer than for the polystyrene homopolymer. Therelative weakness of this peak is believed to occur because the metaprotons in the ESI copolymer resonate in the 7.1 ppm region. Thus, theonly protons that produce the 6.6 ppm peak are meta protons associatedwith atactic polystyrene homopolymer that is an impurity in the ESI. Thepeak centered at about 7.1 ppm thus includes ortho, meta and paraprotons from the aromatic rings in the ESI interpolymer, as well as theortho and para protons from the aromatic rings in the polystyrenehomopolymer impurity. The peaks in the aliphatic region includeresonances of aliphatic protons from both the ESI interpolymer and thepolystyrene homopolymer impurity.

Again, the relative intensities of the peaks are determined byintegration. The peak centered around 7.1 ppm is referred to below asI_(7.1), that centered around 6.6 ppm is I_(6.6) and that in thealiphatic regions is I_(al).

I_(7.1) includes a component attributable to the aromatic protons of thearomatic protons of the ESI interpolymer and a component attributable tothe ortho and para protons of the aromatic rings of the polystyrenehomopolymer impurity. Thus,

I _(7.1) =I _(c7.1) +I _(ps7.1)

where I_(c7.1) is the intensity of the 7.1 ppm resonance attributable tothe aromatic protons in the interpolymer and I_(ps7.1) is the intensityof the 7.1 ppm resonance attributable to the ortho and meta protons ofthe polystyrene homopolymer.

From theoretical considerations, as confirmed by the ¹H NMR spectrum ofthe polystyrene homopolymer, the intensity of the 7.1 ppm resonanceattributable to the polystyrene homopolymer impurity (I_(ps7.1)), equals1.5 times the intensity of the 6.6 ppm resonance. This provides a basisfor determining I_(c7.1) from measured values, as follows:

I _(c7.1) =I _(7.1)−1.5(I _(6.6)).

Similarly, I_(al) can be resolved into resonances attributable to theESI and the polystyrene homopolymer impurity using the relationship

I _(al) =I _(cal) +I _(psal)

wherein I_(cal) is the intensity attributable to the aliphatic protonson the interpolymer and I_(psal) is the intensity attributable to thealiphatic protons of the polystyrene homopolymer impurity. Again, it isknown from theoretical considerations and the spectrum from the atacticpolystyrene homopolymer that I_(psal) will equal 1.5 times I_(6.6). Thusthe following relationship provides a basis for determining I_(cal) frommeasured values:

I _(cal) =I _(al)−1.5(I _(6.6)).

The mole percent ethylene and styrene in the interpolymer are thencalculated as follows:

s _(c) =I _(c7.1)/5

e _(c)=(I _(cal)−(3×s _(c)))/4

E=e _(c)/(s _(c) +e _(c)), and

S=s _(c)/(s _(c) +e _(c)),

wherein E and S are the mole fractions of copolymerized ethylene andstyrene, respectively, contained in the interpolymer.

Weight percent ethylene and styrene are calculated using the equations${{Wt}\% \quad E} = {{\frac{100\%*28\quad E}{\left( {{28\quad E} + {104\quad S}} \right)}\quad {and}\quad {Wt}\% \quad S} = {\frac{100\%*104\quad S}{\left( {{28\quad E} + {104\quad S}} \right)}.}}$

The weight percent of polystyrene homopolymer impurity in the ESI sampleis then determined by the following equation:${{Wt}\% \quad {PS}} = {\frac{100\%*{Wt}\% \quad S*\left( {{I_{6.6}/2}S} \right)}{100 - \left\lbrack {{Wt}\% \quad S*\left( {{I_{6.6}/2}S} \right)} \right\rbrack}.}$

The total styrene content was also determined by quantitative FourierTransform Infrared spectroscopy (FTIR).

Preparation of Ethylene/Styrene Interpolymers (“ESI's”) Used in Examplesand Comparative Experiments of Present Invention

1) Preparation of ESI #'s 1-7

ESI #'s 1-7 are substantially random ethylene/styrene interpolymersprepared using the following catalysts.

Preparation of Catalyst A(dimethyl[N-(1,1-dimethylethyl)-1,1-dimethyl-1-[(1,2,3,4,5-η)-1,5,6,7-tetrahydro-3-phenyl-s-indacen-1-yl]silanaminato(2-)-N]-titanium)

1) Preparation of 3,5,6,7-Tetrahydro-s-Hydrindacen-1(2H)-one

Indan (94.00 g, 0.7954 moles) and 3-chloropropionyl chloride (100.99 g,0.7954 moles) were stirred in CH₂Cl₂ (300 mL) at 0° C. as AlCl₃ (130.00g, 0.9750 moles) was added slowly under a nitrogen flow. The mixture wasthen allowed to stir at room temperature for 2 hours. The volatiles werethen removed. The mixture was then cooled to 0° C. and concentratedH₂SO₄ (500 mL) slowly added. The forming solid had to be frequentlybroken up with a spatula as stirring was lost early in this step. Themixture was then left under nitrogen overnight at room temperature. Themixture was then heated until the temperature readings reached 90° C.These conditions were maintained for a 2 hour period of time duringwhich a spatula was periodically used to stir the mixture. After thereaction period crushed ice was placed in the mixture and moved around.The mixture was then transferred to a beaker and washed intermittentlywith H₂O and diethylether and then the fractions filtered and combined.The mixture was washed with H₂O (2×200 mL). The organic layer was thenseparated and the volatiles removed. The desired product was thenisolated via recrystallization from hexane at 0° C. as pale yellowcrystals (22.36 g, 16.3% yield).

¹H NMR (CDCl₃): d2.04-2.19 (m, 2 H), 2.65 (t, ³J_(HH)=5.7 Hz, 2 H),2.84-3.0 (m, 4 H), 3.03 (t, ³J_(HH)=5.5 Hz, 2 H), 7.26 (s, 1 H), 7.53(s, 1 H).

¹³C NMR (CDCl₃): d25.71, 26.01, 32.19, 33.24, 36.93, 118.90, 122.16,135.88, 144.06, 152.89, 154.36, 206.50.

GC-MS: Calculated for C₁₂H₁₂O 172.09, found 172.05.

2) Preparation of 1,2,3,5-Tetrahydro-7-phenyl-s-indacen.

3,5,6,7-Tetrahydro-s-Hydrindacen-1(2H)-one (12.00 g, 0.06967 moles) wasstirred in diethyl ether (200 mL) at 0° C. as PhMgBr (0.105 moles, 35.00mL of 3.0 M solution in diethyl ether) was added slowly. This mixturewas then allowed to stir overnight at room temperature. After thereaction period the mixture was quenched by pouring over ice. Themixture was then acidified (pH=1) with HCl and stirred vigorously for 2hours. The organic layer was then separated and washed with H₂O (2×100mL) and then dried over MgSO₄. Filtration followed by the removal of thevolatiles resulted in the isolation of the desired product as a dark oil(14.68 g, 90.3% yield).

¹H NMR (CDCl₃): d2.0-2.2 (m, 2 H), 2.8-3.1 (m, 4 H), 6.54 (s, 1H),7.2-7.6 (m, 7 H).

GC-MS: Calculated for C₁₈H₁₆ 232.13, found 232.05.

3) Preparation of 1,2,3,5-Tetrahydro-7-phenyl-s-indacene, dilithiumsalt.

1,2,3,5-Tetrahydro-7-phenyl-s-indacen (14.68 g, 0.06291 moles) wasstirred in hexane (150 mL) as nBuLi (0.080 moles, 40.00 mL of 2.0 Msolution in cyclohexane) was slowly added. This mixture was then allowedto stir overnight. After the reaction period the solid was collected viasuction filtration as a yellow solid which was washed with hexane, driedunder vacuum, and used without further purification or analysis (12.2075g, 81.1% yield).

4) Preparation ofChlorodimethyl(1,5,6,7-tetrahydro-3-phenyl-s-indacen-1-yl)silane.

1,2,3,5-Tetrahydro-7-phenyl-s-indacene, dilithium salt (12.2075 g,0.05102 moles) in THF (50 mL) was added dropwise to a solution ofMe₂SiCl₂ (19.5010 g, 0.1511 moles) in THF (100 mL) at 0° C. This mixturewas then allowed to stir at room temperature overnight. After thereaction period the volatiles were removed and the residue extracted andfiltered using hexane. The removal of the hexane resulted in theisolation of the desired product as a yellow oil (15.1492 g, 91.1%yield).

¹H NMR (CDCl₃): d0.33 (s, 3 H), 0.38 (s, 3 H), 2.20 (p, ³J_(HH)=7.5 Hz,2 H), 2.9-3.1 (m, 4 H), 3.84 (s, 1 H), 6.69 (d, ³J_(HH)=2.8 Hz, 1 H),7.3-7.6 (m, 7 H), 7.68 (d, ³J_(HH)=7.4 Hz, 2 H).

¹³C NMR (CDCl₃): d0.24, 0.38, 26.28, 33.05, 33.18, 46.13, 116.42,119.71, 127.51, 128.33, 128.64, 129.56, 136.51, 141.31, 141.86, 142.17,142.41, 144.62.

GC-MS: Calculated for C₂₀H₂₁ClSi 324.11, found 324.05.

5) Preparation ofN-(1,1-Dimethylethyl)-1,1-dimethyl-1-(1,5,6,7-tetrahydro-3-phenyl-s-indacen-1-yl)silanamine.

Chlorodimethyl(1,5,6,7-tetrahydro-3-phenyl-s-indacen-1-yl)silane(10.8277 g, 0.03322 moles) was stirred in hexane (150 mL) as NEt₃(3.5123 g, 0.03471 moles) and t-butylamine (2.6074 g, 0.03565 moles)were added. This mixture was allowed to stir for 24 hours. After thereaction period the mixture was filtered and the volatiles removedresulting in the isolation of the desired product as a thick red-yellowoil (10.6551 g, 88.7% yield).

¹H NMR (CDCl₃): d0.02 (s, 3 H), 0.04 (s, 3 H), 1.27 (s, 9 H), 2.16 (p,³J_(HH)=7.2 Hz, 2 H), 2.9-3.0 (m, 4 H), 3.68 (s, 1 H), 6.69 (s, 1 H),7.3-7.5 (m, 4 H), 7.63 (d, ³J_(HH)=7.4 Hz, 2 H).

¹³C NMR (CDCl₃): d−0.32, −0.09, 26.28, 33.39, 34.11, 46.46, 47.54,49.81, 115.80, 119.30, 126.92, 127.89, 128.46, 132.99, 137.30, 140.20,140.81, 141.64, 142.08, 144.83.

6) Preparation ofN-(1,1-Dimethylethyl)-1,1-dimethyl-1-(1,5,6,7-tetrahydro-3-phenyl-s-indacen-1-yl)silanamine, dilithium salt.

N-(1,1-Dimethylethyl)-1,1-dimethyl-1-(1,5,6,7-tetrahydro-3-phenyl-s-indacen-1-yl)silanamine(10.6551 g, 0.02947 moles) was stirred in hexane (100 mL) as nBuLi(0.070 moles, 35.00 mL of 2.0 M solution in cyclohexane) was addedslowly. This mixture was then allowed to stir overnight during whichtime no salts crashed out of the dark red solution. After the reactionperiod the volatiles were removed and the residue quickly washed withhexane (2×50 mL). The dark red residue was then pumped dry and usedwithout further purification or analysis (9.6517 g, 87.7% yield).

7) Preparation ofDichloro[N-(1,1-dimethylethyl)-1,1-dimethyl-1-[(1,2,3,4,5-η)-1,5,6,7-tetrahydro-3-phenyl-s-indacen-1-yl]silanaminato(2-)-N]titanium

N-(1,1-Dimethylethyl)-1,1-dimethyl-1-(1,5,6,7-tetrahydro-3-phenyl-s-indacen-1-yl)silanamine,dilithium salt (4.5355 g, 0.01214 moles) in THF (50 mL) was addeddropwise to a slurry of TiCl₃(THF)₃ (4.5005 g, 0.01214 moles) in THF(100 mL). This mixture was allowed to stir for 2 hours. PbCl₂ (1.7136 g,0.006162 moles) was then added and the mixture allowed to stir for anadditional hour. After the reaction period the volatiles were removedand the residue extracted and filtered using toluene. Removal of thetoluene resulted in the isolation of a dark residue. This residue wasthen slurried in hexane and cooled to 0° C. The desired product was thenisolated via filtration as a red-brown crystalline solid (2.5280 g,43.5% yield).

¹H NMR (CDCl₃): d0.71 (s, 3 H), 0.97 (s, 3 H), 1.37 (s, 9 H), 2.0-2.2(m, 2 H), 2.9-3.2 (m, 4 H), 6.62 (s, 1 H), 7.35-7.45 (m, 1 H), 7.50 (t,³J_(HH)=7.8 Hz, 2 H), 7.57 (s, 1 H), 7.70 (d, ³J_(HH)=7.1 Hz, 2 H), 7.78(s, 1 H).

¹H NMR (C₆D₆): d0.44 (s, 3 H), 0.68 (s, 3 H), 1.35 (s, 9 H), 1.6-1.9 (m,2 H), 2.5-3.9 (m, 4 H), 6.65 (s, 1 H), 7.1-7.2 (m, 1 H), 7.24 (t,³J_(HH)=7.1 Hz, 2 H), 7.61 (s, 1 H), 7.69 (s, 1 H), 7.77-7.8 (m, 2 H).

¹³C NMR (CDCl₃): d1.29, 3.89, 26.47, 32.62, 32.84, 32.92, 63.16, 98.25,118.70, 121.75, 125.62, 128.46, 128.55, 128.79, 129.01, 134.11, 134.53,136.04, 146.15, 148.93.

¹³C NMR (C₆D₆): d0.90, 3.57, 26.46, 32.56, 32.78, 62.88, 98.14, 119.19,121.97, 125.84, 127.15, 128.83, 129.03, 129.55, 134.57, 135.04, 136.41,136.51, 147.24, 148.96.

8) Preparation ofDimethyl[N-(1,1-dimethylethyl)-1,1-dimethyl-1-[(1,2,3,4,5-η)-1,5,6,7-tetrahydro-3-phenyl-s-indacen-1-yl]silanaminato(2-)-N]titanium

Dichloro[N-(1,1-dimethylethyl)-1,1-dimethyl-1-[(1,2,3,4,5-η)-1,5,6,7-tetrahydro-3-phenyl-s-indacen-1-yl]silanaminato(2-)-N]titanium(0.4970 g, 0.001039 moles) was stirred in diethylether (50 mL) as MeMgBr(0.0021 moles, 0.70 mL of 3.0 M solution in diethylether) was addedslowly. This mixture was then stirred for 1 hour. After the reactionperiod the volatiles were removed and the residue extracted and filteredusing hexane. Removal of the hexane resulted in the isolation of thedesired product as a golden yellow solid (0.4546 g, 66.7% yield).

¹H NMR (C₆D₆): d0.071 (s, 3 H), 0.49 (s, 3 H), 0.70 (s, 3 H), 0.73 (s, 3H), 1.49 (s, 9 H), 1.7-1.8 (m, 2 H), 2.5-2.8 (m, 4H), 6.41 (s, 1 H),7.29 (t, ³J_(HH)=7.4 Hz, 2 H), 7.48 (s, 1 H), 7.72 (d, ³J_(HH)=7.4 Hz, 2H), 7.92 (s, 1 H).

¹³C NMR (C₆D₆): d2.19, 4.61, 27.12, 32.86, 33.00, 34.73, 58.68, 58.82,118.62, 121.98, 124.26, 127.32, 128.63, 128.98, 131.23, 134.39, 136.38,143.19, 144.85.

Preparation of Catalyst B;(1H-cyclopenta[1]phenanthrene-2-yl)dimethyl(t-butylamido)-silanetitanium1,4-diphenylbutadiene)

1) Preparation of lithium 1H-cyclopenta[1]phenanthrene-2-yl

To a 250 ml round bottom flask containing 1.42 g (0.00657 mole) of1H-cyclopenta[1]phenanthrene and 120 ml of benzene was added dropwise,4.2 ml of a 1.60 M solution of n-BuLi in mixed hexanes. The solution wasallowed to stir overnight. The lithium salt was isolated by filtration,washing twice with 25 ml benzene and drying under vacuum. Isolated yieldwas 1.426 g (97.7 percent). 1H NMR analysis indicated the predominantisomer was substituted at the 2 position.

2) Preparation of(1H-cyclopenta[1]phenanthrene-2-yl)dimethylchlorosilane

To a 500 ml round bottom flask containing 4.16 g (0.0322 mole) ofdimethyldichlorosilane (Me₂SiCl₂) and 250 ml of tetrahydrofuran (THF)was added dropwise a solution of 1.45 g (0.0064 mole) of lithium1H-cyclopenta[1]phenanthrene-2-yl in THF. The solution was stirred forapproximately 16 hours, after which the solvent was removed underreduced pressure, leaving an oily solid which was extracted withtoluene, filtered through diatomaceous earth filter aid (Celite™),washed twice with toluene and dried under reduced pressure. Isolatedyield was 1.98 g (99.5 percent).

3. Preparation of(1H-cyclopenta[1]phenanthrene-2-yl)dimethyl(t-butylamino)silane

To a 500 ml round bottom flask containing 1.98 g (0.0064 mole) of(1H-cyclopenta[1]phenanthrene-2-yl)dimethylchlorosilane and 250 ml ofhexane was added 2.00 ml (0.0160 mole) of t-butylamine. The reactionmixture was allowed to stir for several days, then filtered usingdiatomaceous earth filter aid (Celite™), washed twice with hexane. Theproduct was isolated by removing residual solvent under reducedpressure. The isolated yield was 1.98 g (88.9 percent).

4. Preparation ofdilithio(1H-cyclopenta[1]phenanthrene-2-yl)dimethyl(t-butylamido)silane

To a 250 ml round bottom flask containing 1.03 g (0.0030 mole) of(1H-cyclopenta[1]phenanthrene-2-yl)dimethyl(t-butylamino)silane) and 120ml of benzene was added dropwise 3.90 ml of a solution of 1.6 M n-BuLiin mixed hexanes. The reaction mixture was stirred for approximately 16hours. The product was isolated by filtration, washed twice with benzeneand dried under reduced pressure. Isolated yield was 1.08 g (100percent).

5. Preparation of(1H-cyclopenta[1]phenanthrene-2-yl)dimethyl(t-butylamido)silanetitaniumdichloride

To a 250 ml round bottom flask containing 1.17 g (0.0030 mole) ofTiCl₃.3THF and about 120 ml of THF was added at a fast drip rate about50 ml of a THF solution of 1.08 g of dilithio(1H-cyclopenta[1]phenanthrene-2-yl)dimethyl(t-butylamido)silane. Themixture was stirred at about 20° C. for 1.5 h at which time 0.55 gm(0.002 mole) of solid PbCl₂ was added. After stirring for an additional1.5 h the THF was removed under vacuum and the reside was extracted withtoluene, filtered and dried under reduced pressure to give an orangesolid. Yield was 1.31 g (93.5 percent).

6. Preparation of(1H-cyclopenta[1]phenanthrene-2-yl)dimethyl(t-butylamido)silanetitanium1,4-diphenylbutadiene

To a slurry of(1H-cyclopenta[1]phenanthrene-2-yl)dimethyl(t-butylamido)silanetitaniumdichloride (3.48 g, 0.0075 mole) and 1.551 gm (0.0075 mole) of1,4-diphenyllbutadiene in about 80 ml of toluene at 70° C. was add 9.9ml of a 1.6 M solution of n-BuLi (0.0150 mole). The solution immediatelydarkened. The temperature was increased to bring the mixture to refluxand the mixture was maintained at that temperature for 2 hrs. Themixture was cooled to about −20° C. and the volatiles were removed underreduced pressure. The residue was slurried in 60 ml of mixed hexanes atabout 20° C. for approximately 16 hours. The mixture was cooled to about−25° C. for about 1 h. The solids were collected on a glass frit byvacuum filtration and dried under reduced pressure. The dried solid wasplaced in a glass fiber thimble and solid extracted continuously withhexanes using a soxhlet extractor. After 6 h a crystalline solid wasobserved in the boiling pot. The mixture was cooled to about −20° C.,isolated by filtration from the cold mixture and dried under reducedpressure to give 1.62 g of a dark crystalline solid. The filtrate wasdiscarded. The solids in the extractor were stirred and the extractioncontinued with an additional quantity of mixed hexanes to give anadditional 0.46 gm of the desired product as a dark crystalline solid.

Polymerization for ESI #'s 1-2

ESI's 1-2 were prepared in a 6 gallon (22.7 L), oil jacketed, Autoclavecontinuously stirred tank reactor (CSTR). A magnetically coupledagitator with Lightning A-320 impellers provided the mixing. The reactorran liquid full at 475 psig (3,275 kPa). Process flow was in at thebottom and out of the top. A heat transfer oil was circulated throughthe jacket of the reactor to remove some of the heat of reaction. At theexit of the reactor was a micromotion flow meter that measured flow andsolution density. All lines on the exit of the reactor were traced with50 psi (344.7 kPa) steam and insulated.

Toluene solvent was supplied to the reactor at 30 psig (207 kPa). Thefeed to the reactor was measured by a Micro-Motion mass flow meter. Avariable speed diaphragm pump controlled the feed rate. At the dischargeof the solvent pump, a side stream was taken to provide flush flows forthe catalyst injection line (1 lb/hr (0.45 kg/hr)) and the reactoragitator (0.75 lb/hr (0.34 kg/hr)). These flows were measured bydifferential pressure flow meters and controlled by manual adjustment ofmicro-flow needle valves. Uninhibited styrene monomer was supplied tothe reactor at 30 psig (207 kpa). The feed to the reactor was measuredby a Micro-Motion mass flow meter. A variable speed diaphragm pumpcontrolled the feed rate. The styrene stream was mixed with theremaining solvent stream.

Ethylene was supplied to the reactor at 600 psig (4,137 kPa). Theethylene stream was measured by a Micro-Motion mass flow meter justprior to the Research valve controlling flow. A Brooks flowmeter/controller was used to deliver hydrogen into the ethylene streamat the outlet of the ethylene control valve. The ethylene/hydrogenmixture combines with the solvent/styrene stream at ambient temperature.The temperature of the solvent/monomer as it enters the reactor wasdropped to ˜5° C. by an exchanger with −5° C. glycol on the jacket. Thisstream entered the bottom of the reactor.

The three component catalyst system and its solvent flush also enteredthe reactor at the bottom but through a different port than the monomerstream. Preparation of the catalyst components took place in an inertatmosphere glove box. The diluted components were put in nitrogen paddedcylinders and charged to the catalyst run tanks in the process area.From these run tanks the catalyst was pressured up with piston pumps andthe flow was measured with Micro-Motion mass flow meters. The flow wasadjusted to maintain the desired ethylene conversion. These streamscombine with each other and the catalyst flush solvent just prior toentry through a single injection line into the reactor.

Polymerization was stopped with the addition of catalyst kill (watermixed with solvent) into the reactor product line after the micromotionflow meter measuring the solution density. Other polymer additives canbe added with the catalyst kill. A static mixer in the line provideddispersion of the catalyst kill and additives in the reactor effluentstream. This stream next entered post reactor heaters that provideadditional energy for the solvent removal flash. This flash occurred asthe effluent exited the post reactor heater and the pressure was droppedfrom 475 psig (3,275 kPa) down to ˜250 mm of pressure absolute at thereactor pressure control valve. This flashed polymer entered a hot oiljacketed devolatilizer. Approximately 85 percent of the volatiles wereremoved from the polymer in the devolatilizer. The volatiles exited thetop of the devolatilizer. The stream was condensed with a glycoljacketed exchanger and entered the suction of a vacuum pump and wasdischarged to a glycol jacket solvent and styrene/ethylene separationvessel. Solvent and styrene were removed from the bottom of the vesseland ethylene from the top. The ethylene stream was measured with aMicro-Motion mass flow meter and analyzed for composition. Themeasurement of vented ethylene plus a calculation of the dissolvedgasses in the solvent/styrene stream were used to calculate the ethyleneconversion. The polymer separated in the devolatilizer was pumped outwith a gear pump to a ZSK-30 devolatilizing vacuum extruder. The drypolymer exits the extruder as a single strand. This strand was cooled asit was pulled through a water bath. The excess water was blown from thestrand with air and the strand was chopped into pellets with a strandchopper.

Polymerization for ESI's 3-7

ESI's 3-7 were prepared in a continuously operating loop reactor (36.8gal. 139 L). An Ingersoll-Dresser twin screw pump provided the mixing.The reactor ran liquid full at 475 psig (3,275 kPa) with a residencetime of approximately 25 minutes. Raw materials and catalyst/cocatalystflows were fed into the suction of the twin screw pump through injectorsand Kenics static mixers. The twin screw pump discharged into a 2″diameter line which supplied two Chemineer-Kenics 10-68 Type BEMMulti-Tube heat exchangers in series. The tubes of these exchangerscontained twisted tapes to increase heat transfer. Upon exiting the lastexchanger, loop flow returned through the injectors and static mixers tothe suction of the pump. Heat transfer oil was circulated through theexchangers' jacket to control the loop temperature probe located justprior to the first exchanger. The exit stream of the loop reactor wastaken off between the two exchangers. The flow and solution density ofthe exit stream was measured by a MicroMotion.

Solvent feed to the reactor was supplied by two different sources. Afresh stream of toluene from an 8480-S-E Pulsafeeder diaphragm pump withrates measured by a MicroMotion flowmeter was used to provide flush flowfor the reactor seals (20 lb/hr (9.1 kg/hr). Recycle solvent was mixedwith uninhibited styrene monomer on the suction side of five 8480-5-EPulsafeeder diaphragm pumps in parallel. These five Pulsafeeder pumpssupplied solvent and styrene to the reactor at 650 psig (4,583 kPa).Fresh styrene flow was measured by a MicroMotion flowmeter, and totalrecycle solvent/styrene flow was measured by a separate MicroMotionflowmeter. Ethylene was supplied to the reactor at 687 psig (4,838 kPa).The ethylene stream was measured by a Micro-Motion mass flowmeter. ABrooks flowmeter/controller was used to deliver hydrogen into theethylene stream at the outlet of the ethylene control valve.

The ethylene/hydrogen mixture combined with the solvent/styrene streamat ambient temperature. The temperature of the entire feed stream as itentered the reactor loop was lowered to 2° C. by an exchanger with −10°C. glycol on the jacket. Preparation of the three catalyst componentstook place in three separate tanks: fresh solvent and concentratedcatalyst/cocatalyst premix were added and mixed into their respectiverun tanks and fed into the reactor via variable speed 680-S-AEN7Pulsafeeder diaphragm pumps. As previously explained, the threecomponent catalyst system entered the reactor loop through an injectorand static mixer into the suction side of the twin screw pump. The flowwas adjusted to maintain the desired ethylene conversion. The rawmaterial feed stream was also fed into the reactor loop through aninjector and static mixer downstream of the catalyst injection point butupstream of the twin screw pump suction.

Polymerization was stopped with the addition of catalyst kill (watermixed with solvent) into the reactor product line after the Micro Motionflowmeter measuring the solution density. A static mixer in the lineprovided dispersion of the catalyst kill and additives in the reactoreffluent stream. This stream next entered post reactor heaters thatprovided additional energy for the solvent removal flash. This flashoccurred as the effluent exited the post reactor heater and the pressurewas dropped from 475 psig (3,275 kPa) down to 450 mmHg (60 kPa) ofabsolute pressure at the reactor pressure control valve.

This flashed polymer entered the first of two hot oil jacketeddevolatilizers. The volatiles flashing from the first devolatizer werecondensed with a glycol jacketed exchanger, passed through the suctionof a vacuum pump, and were discharged to the solvent andstyrene/ethylene separation vessel. Solvent and styrene were removedfrom the bottom of this vessel as recycle solvent while ethyleneexhausted from the top. The ethylene stream was measured with aMicroMotion mass flowmeter. The measurement of vented ethylene plus acalculation of the dissolved gases in the solvent/styrene stream wereused to calculate the ethylene conversion. The polymer and remainingsolvent separated in the devolatilizer was pumped with a gear pump to asecond devolatizer. The pressure in the second devolatizer was operatedat 5 mm Hg (0.7 kPa) absolute pressure to flash the remaining solvent.This solvent was condensed in a glycol heat exchanger, pumped throughanother vacuum pump, and exported to a waste tank for disposal. The drypolymer (<1000 ppm total volatiles) was pumped with a gear pump to anunderwater pelletizer with 6-hole die, pelletized, spin-dried, andcollected in 1000 lb boxes.

The various catalysts, co-catalysts and process conditions used toprepare the various individual ethylene styrene interpolymers (ESI #'s1-7) are summarized in Table 1 and their properties are summarized inTable 2.

TABLE 1 Preparation Conditions for ESI #'s 1-7 Reactor Solvent HydrogenStyrene Ethylene B/Ti MMAO^(d)/ ESI Temp Flow Ethylene Flow Flow FlowConversion Mol Ti Mol Co- # ° C. lb/hr lb/hr sccm lb/hr % Ratio RatioCatalyst Catalyst ESI 1- 93.0 37.9 3.1 13.5 6.9 96.21 2.99 7.0 A^(a)C^(c) ESI 2 79.0 31.3 1.74 4.3 13.5 95.1 3.51 9.0 A^(a) C^(c) ESI-3 88.0590 55 250 133 94.0 3.50 4.9 B^(b) C^(c) ESI-4 83.0 445 43 235 91 94.06.00 16.0 B^(b) C^(c) ESI-5 61.0 386 20 0 100 88 3.50 2.5 B^(b) C^(c)ESI-6 87.0 800 83 569 197 93.0 4.00 6.0 B^(b) C^(c) ESI-7 81.0 799 65500 247 95 3.70 6.0 B^(b) C^(c) *N/A = not available ^(a)Catalyst A isdimethyl[N-(1,1-dimethylethyl)-1,1-dimethyl-1-[(1,2,3,4,5-η)-1,5,6,7-tetrahydro-3-phenyl-s-indacen-1-yl]-silanaminato(2-)-N]-titanium.^(b)Catalyst B is;(1H-cyclopenta[1]phenanthrene-2-yl)dimethyl(t-butylamido)silanetitanium1,4-diphenylbutadiene) ^(c)Cocatalyst C istris(pentafluorophenyl)borane, (CAS# 001109-15-5), ^(d)a modifiedmethylaluminoxane commercially available from Akzo Nobel as MMAO-3A(CAS# 146905-79-5)

TABLE 2 Properties of ESI #'s 1-7. wt. % mol. % Melt Index, G #Copolymer Copolymer aPS I₂ (cm³/ ESI # Styrene Styrene wt % (g/10 min)10 min) ESI-1 47.4 19.5 0.5 1.54 ESI-2 69.0 37.5 1.6 1.36 ESI-3 44.617.8 11.5  1.52 ESI-4 63.7 32.1 N/A 0.61 ESI-5 69.5 38.0 8.9 0.94 ESI-661.7 30.2 2.9 0.63 ESI-7 70.6 39.3 6.1 1.17

Additional Blend Components

PS 1 is a granular polystyrene having a weight average molecular weight,Mw, of about 192,000 and a polydispersity, M_(w)/M_(n), of about 2.

PS 2 is a granular polystyrene having a weight average molecular weight,Mw, of about 305,000 and a polydispersity, M_(w)/M_(n), of about 2.

LDPE 1 is a low density polyethylene having a melt index, I₂, of 1.8g/10 min, a weight-average molecular weight of 117,600, a number-averagemolecular weight of 17,200 and a density of 0.9230 g/cm³.

LDPE 2 is a low density polyethylene having a melt index, I₂, of 2.4g/10 min, a weight-average molecular weight of 98,300, a number-averagemolecular weight of 13,300 and a density of 0.9241 g/cm³.

EXAMPLES 1-4

A foaming process comprising a single-screw extruder, mixer, coolers anddie was used to make foam. Isobutane was used as the blowing agent at alevel of 7.5 part-per-hundred resin (phr) to foam LDPE and PS/ESIblends. Table 3 summarizes the foam properties, all of which foams weresoft and flexible to the touch while having small cell size, smoothskin, good dimensional stability, and a wide range of open cellcontents. The foams of the present invention (Ex. 1-4) did not shrinksignificantly as measured by volume change (computed from measurementsof foam mass and density) when cured at room temperature unlike thecomparative non-crosslinked foam made form LDPE (Comp. Ex 1).

TABLE 3 PS/ESI blends, using Isobutane as Blowing Agent Max Vol BlendFoaming foam % Cell Change at Composition temp density open size 23° C.Ex # wt % ° C. kg/m3 cells mm (vol %) Ex 1  50% PS1/ 122 46.2 54.6 0.21−3.2  50% ESI 1 Ex 2  50% PS1/ 112 54.7 87.3 0.30 −3.2  50% ESI 1 Ex 3 50% PS1/ 112 65.2 81.1 0.09 −3.4  50% ESI 2 Ex 4  50% PS1/ 102 74.465.9 0.12 −2.3  50% ESI 2 Comp 100% LDPE 1 112 37.7 4.5 1.63 −28.5 Ex. 1

EXAMPLE 5-9

A foaming process comprising a single-screw extruder, mixer, coolers anddie was used to make foam planks. Isobutane and HCFC-142b were used asblowing agents to foam LDPE and blends of polystyrene with ESI. ForExamples 5-9 and Comparative Example 2, Irganox™ 1010 (a product andtrademark of Ciba-Geigy) was used at a loading of 0.06 phr. In the caseof Comparative Example 2, additional additives were 0.2 phr ofHydrocerol™ (a product and trademark of Boehringer Ingelheim) CF40E asnucleator, and 0.5 phr of glycerol monostearate as permeabilitymodifier. For Comparative Example 3, the additives used were:hexabromocyclo-dodecane=2.5 phr; barium stearate=0.2 phr; bluepigment=0.15 phr; tetra-sodiumpyrophosphate=0.2 phr; linear low densitypolyethylene=0.4 phr The examples in Table 4 were soft and flexible,close in Asker C hardness to a conventional LDPE foam used for cushionpackaging (Comparative Example 2) and much softer than a foam made froman 80/20 blend of polystyrene/ESI (Comparative Example 3).

TABLE 4 PS/ESI blends Blend Foaming foam density Composition Blowingtemp after 60 days thickness width % open Av. cell Ex # wt % Agent ° C.kg/m3 (mm) (mm) cells size mm Ex 5  60% PS1/ 10 phr 114 25.9 13 170 2.30.57  40% ESI 3 isobutane Ex 6  60% PS1/ 10 phr 114 25.1 22 160 4.3 0.46 40% ESI 4 isobutane Ex 7  50% PS1/ 10 phr 115 24.6 21 158 30.8 0.51 50% ESI 4 isobutane Ex 8  50% PS1/ 10 phr 114 24.6 22 160 34.4 0.48 50% ESI 4 isobutane Ex 9  50% PS1/ 10 phr 110 28.8 20 150 58.3 0.62 50% ESI 4 isobutane Comp Ex. 2 100% LDPE 2 10 phr 111 29.8 21 146 17.71.23 isobutane Comp Ex. 3  80% PS1/ 13 phr 121 32.0 39 145 9.4 0.26  20%ESI 5 HCFC-142b Average Compressive Compression strength kPa (25% Set(%) after Max. Linear compression, ASTM 60 days Hardness Change at 70°C. Lambda (10° C.) Ex # 3575) after 60 days (DIN 53572) (Asker C) (%)mW/m K Ex 5 97 6.8 45 +2.0 32.6 Ex 6 93 4.7 43 −1.2 31.8 Ex 7 52 15.3 32−2.8 34.2 Ex 8 56 17.2 33 −2.6 34.7 Ex 9 46 17.4 33 −3.2 34.3 Comp Ex. 263 5.2 28 −1.0 N/A Comp Ex. 3 N/A N/A 67 N/A 28.3

EXAMPLE 10

A foaming process comprising a single-screw extruder, mixer, coolers anddie was used to make foam planks. Isobutane or isobutane/carbon dioxidemixtures were used as blowing agents to foam blends of polystyrene withESI. The foams were soft and flexible with smooth skin, small cells andAsker C hardness of about 50 or less.

TABLE 5 PS/ESI blends using Isobutane and/or CO₂ as Blowing Agents TotalCompressive Blend foam density % open Av. strength kPa after 28Composition Blowing Foaming after 7 days thickness width cells Cell daysHardness Ex # wt % Agent temp ° C. kg/m3 (mm) (mm) (ASTM D285694) sizemm (ASTM D162194) (Asker C) Ex 10 50% PS2/ 8.6 phr 115 29.17 27 93 81.10.44 354 40 50% ESI 6 isobutane and 1 phr CO2 Ex. 11 50% PS2/ 10 phr 12028.05 20 93 22.3 0.52 973 50 50% ESI 7 isobutane

EXAMPLE 12 Foams Used as Acoustical Insulator

The foam of Example 7 was elastified and its acoustical performance wascompared to that of an elastified expanded polystyrene (EPS) foam(Techmate™ AC a product and registered trademark of The Dow ChemicalCompany. The foam of Example 7 was elastified by passing between twosteel rolls (with a gap of 15% of the original foam thickness) threetimes thus compressing the material by 85%. The pull rate of the rollswas 2 m/sec. No holding time was applied, the foam was just passedthrough the rollers. A 10-minute interval was allowed between eachelastification step The elastified samples were of approximately 10 mmthickness. The foam had a vertical compressive strength (at 25%compression) of 24 kPa after elastification. The compressive strengthwas measured per a method described in ASTM D 3575.

As shown in Table 6, the foam of Example 12 shows the same impact soundreduction as the thicker elastified EPS foam at a significantly higherdynamic stiffness and at a significantly smaller thickness. The 25 dBreduction in impact sound obtained with the foam of Example 12 wassurprisingly high. The result was unexpected because the measureddynamic stiffness of the material (52 MN/m³) in combination with theused screed mass of 100 kg/m² was anticipated to result in an impactsound reduction level ΔLw of 22 dB. under prEN 12354-2:1996. The testwas performed at “Fraunhofer Institut für Bauphysik” at Stuttgart and isreported in the test report number P-BA 167/1999. According to prEN12354-2:1996, a dynamic stiffness as low as 33 MN/m³ is required toachieve this performance with a conventional material.

Since the dynamic stiffness is defined as the dynamic modulus divided bythe thickness of the material, a conventional material would need to be60% thicker to achieve the same impact sound improvement level as thematerial in accordance with the present invention. Conversely, asubstantially thinner foam insulation of the present invention may beused rather than a thicker foam from conventional material, therebysaving not only the material but also the space. The superior soundinsulation performance of the foams of the present invention is believedpartly to come from its higher damping capability than an EPS material.The foam of Example 12 showed a damping ratio of 18.8% as compared to7.35 for the elastified EPS foam of Comparative Example 4. Ordinarily, adamping ratio above 10 would have a positive effect on impact soundinsulation while one below 10 would have little effect on impact soundinsulation.

TABLE 6 Acoustical Insulation Data Dynamic Thick- Stiffness ness DampingΔLw Ex # Foam (MN/m³) (mm) Ratio (dB) Comp Ex 4 Techmate AC 32 17 18.825 Ex 12 Elastified Ex 7 52 10  7.3 25

What is claimed is:
 1. A process for making an extruded soft foam havingan Asker C hardness of less than about 65, which process comprises; (I)forming a melt polymer material comprising; (A) one or more alkenylaromatic polymers, and wherein at least one of said alkenyl aromaticpolymers has a molecular weight (M_(w)) of from about 100,000 to about500,000; and (B) one or more substantially random interpolymers havingan I₂ of about 0.1 to about 50 g/10 min, an M_(w)/M_(n) of about 1.5 toabout 20,; comprising; (1) polymer units derived from; (a) at least onevinyl or vinylidene aromatic monomer, or (b) at least one hinderedaliphatic or cycloaliphatic vinyl or vinylidene monomer, or (c) acombination of at least one aromatic vinyl or vinylidene monomer and atleast one hindered aliphatic or cycloaliphatic vinyl or vinylidenemonomer, and (2) polymer units derived from at least one of ethyleneand/or a C₃₋₂₀ α-olefin; and (3) optionally polymer units derived fromone or more of ethylenically unsaturated polymerizable monomers otherthan those derived from (1) and (2); and (C) optionally, one or morenucleating agents and (D) optionally, one or more other additives; and(II) incorporating into said melt polymer material at an elevatedpressure to form a foamable gel (E) one or more blowing agents presentin a total amount of from about 0.4 to about 5.0 gram-moles per kilogram(based on the combined weight of Components A and B); (III) cooling saidfoamable gel to an optimum temperature; and extrude said foamable gelfrom Step III either (a) through a die to a region of lower pressure toform a foam or, (b) into a holding zone maintained at a temperature andpressure which does not allow the gel to foam, the holding zone havingan outlet die defining an orifice opening into a zone of lower pressureat which the gel foams, and an openable gate closing the die orifice;periodically opening the gate; substantially concurrently applyingmechanical pressure by a movable ram on the gel to eject it from theholding zone through the die orifice into the zone of lower pressure, ata rate greater than that at which substantial foaming in the die orificeoccurs and less than that at which substantial irregularities incross-sectional area or shape occurs; and permitting the ejected gel toexpand unrestrained in at least one dimension to produce the foamstructure.
 2. The process of claim 1 wherein the foamable gel from step(II) is cooled to an optimum temperature at which foaming does not occurand then extruded through a die to form an essentially continuousexpandable thermoplastic strand which is pelletized to form expandablethermoplastic beads.
 3. The process of claim 1 wherein in step (IV) saidfoamable gel is extruded through a die to form essentially continuousexpanded thermoplastic strands which are converted to foam beads bycutting at the die face and then allowed to expand.
 4. A process formaking a soft foam having an Asker C hardness of less than about 65 inthe form of thermoplastic foam beads, which process comprises; (I)forming a melt polymer material comprising; (A) one or more alkenylaromatic polymers, and wherein at least one of said alkenyl aromaticpolymers has a molecular weight (M_(w)) of from about 100,000 to about500,000; and (B) one or more substantially random interpolymers havingan I₂ of about 0.1 to about 50 g/10 min, an M_(w)/M_(n) of about 1.5 toabout 20, comprising; (1) polymer units derived from; (a) at least onevinyl or vinylidene aromatic monomer, or (b) at least one hinderedaliphatic or cycloaliphatic vinyl or vinylidene monomer, or (c) acombination of at least one aromatic vinyl or vinylidene monomer and atleast one hindered aliphatic or cycloaliphatic vinyl or vinylidenemonomer, and (2) polymer units derived from at least one of ethyleneand/or a C₃₋₂₀ α-olefin; and (3) optionally polymer units derived fromone or more of ethylenically unsaturated polymerizable monomers otherthan those derived from (1) and (2); and (C) optionally, one or morenucleating agents; and (D) optionally, one or more other additives; and(II) cooling and granulating the product from step I to form discreteresin particles; and (III) suspending said resin particles in a liquidmedium in which they are substantially insoluble; (IV) incorporatinginto the suspension formed in Step III at an elevated pressure andtemperature in an autoclave or other pressure vessel; (E) one or moreblowing agents present in a total amount of from about 0.4 to about 5.0gram-moles per kilogram (based on the combined weight of Components Aand B); and (V) rapidly discharging the product formed in Step IV intothe atmosphere, or a region of reduced pressure, to form foam beads. 5.A process for making a soft foam having an Asker C hardness of less thanabout 65 in the form of thermoplastic foam beads, which comprises; (I)impregnation of styrene monomer into suspended pellets of one or moresubstantially random interpolymer(s) in a vessel at elevated temperaturein the presence of a peroxide initiator to form a grafted polymer ofpolystyrene with the substantially random polymer; (II) impregnation ofthe product of step I with one or more blowing agents present in a totalamount of from about 0.4 to about 5.0 gram-moles per kilogram (based onthe weight of the grafted polymer formed in Step I); (III) cooling anddischarging the product from step II to form unexpanded beads; and (IV)expanding and molding the beads of step III to form a foam; wherein saidgrafted polymer formed in step I comprises; (A) one or more alkenylaromatic polymers, and wherein at least one of said alkenyl aromaticpolymers has a molecular weight (M_(w)) of from about 100,000 to about500,000; and (B) one or more substantially random interpolymers havingan I₂ of about 0.1 to about 50 g/10 min, an M_(w)/M_(n) of about 1.5 toabout 20, comprising; (1) polymer units derived from; (a) at least onevinyl or vinylidene aromatic monomer, or (b) at least one hinderedaliphatic or cycloaliphatic vinyl or vinylidene monomer, or (c) acombination of at least one aromatic vinyl or vinylidene monomer and atleast one hindered aliphatic or cycloaliphatic vinyl or vinylidenemonomer, and (2) polymer units derived from at least one of ethyleneand/or a C₃₋₂₀ α-olefin; and (3) optionally, polymer units derived fromone or more of ethylenically unsaturated polymerizable monomers otherthan those derived from (1) and (2); and (C) optionally, one or morenucleating agents; and (D) optionally, one or more other additives.